Check probes only when deployed

Aim: Test probes in update_endstops only when activated

Changes:
Configurations
 Add define for FIX_MOUNTED_PROBE to handle the situation where formerly ENDSTOPS_ONLY_FOR_HOMING had to be set, or lowering the nozzle below Z_PROBE_OFFSET_FROM_EXTRUDER could give an "endstop hit" message.
 Add define for Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN to indicate a common situation, that we have a probe but it is connected to an endstop pin
 Add some comments
 Shift some entries to have related things together.

Conditionals.h
 We have a probe (HAS_Z_MIN_PROBE) if one of the pins is defined AND one of the probes is defined.

SanityCheck.h
 Add some tests if the probe is connected and if we have defined a probe.

stepper.cpp
 Changes to test the probe only when it is deployed (z_probe_is_active).
 Test update_endstops() when the probe is deployed.

MarlinMain.cpp
 a. set and reset z_probe_is_active in deploy_z_probe(), stow_z_probe() and dock_sled()
 b. set and reset z_probe_is_active in the case a z-servo is moved to a defined position. The only remaining unhandled servo move is in M280 where we do not end in a defined position. If you want to handle a probe use M401/402
 c. skip deploying/stowing when already deployed/stowed in the dedicated deploy/stow functions.
 d. Handle the new FIX_MOUNTED_PROBE in parallel to a servo driven probe/endstop.

 To do: In another PR. handle all probes in deploy/stow_z_probe.
 Sort out SERVO_LEVELING vs. HAS_SERVO_ENDSTOPS.

Marlin/Conditionals.h

     #endif
   #endif
 
+  #if ( (HAS_Z_MIN && ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)) || HAS_Z_PROBE ) && \
+    ( ENABLED(FIX_MOUNTED_PROBE) || defined(Z_ENDSTOP_SERVO_NR) || ENABLED(Z_PROBE_ALLEN_KEY) || ENABLED(Z_PROBE_SLED) )
+    #define HAS_Z_MIN_PROBE
+  #endif
+
 #endif //CONFIGURATION_LCD
 #endif //CONDITIONALS_H

Marlin/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
-// If you want to enable the Z probe pin, but disable its use, uncomment the line below.
-// This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
-// this has no effect.
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// Enable Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN to use the Z_MIN_PIN for your Z_MIN_PROBE.
+// The Z_MIN_PIN will then be used for both Z-homing and probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+
+// To use a probe you must enable one of the two options above!
+
+// This option disables the use of the Z_MIN_PROBE_PIN
+// To enable the Z probe pin but disable its use, uncomment the line below. This only affects a
+// Z probe switch if you have a separate Z min endstop also and have activated Z_MIN_PROBE_ENDSTOP above.
+// If you're using the Z MIN endstop connector for your Z probe, this has no effect.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
-  //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
-  //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // An Allen Key Probe is currently predefined only in the delta example configurations.
 
+  //#define Z_PROBE_SLED // Enable if you have a Z probe mounted on a sled like those designed by Charles Bell.
+  //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
-  //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
-  //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
+  // If you've enabled AUTO_BED_LEVELING_FEATURE and are using the Z Probe for Z Homing,
+  // it is highly recommended you leave Z_SAFE_HOMING enabled!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/Marlin_main.cpp

   float extrude_min_temp = EXTRUDE_MINTEMP;
 #endif
 
+#if ENABLED(HAS_Z_MIN_PROBE)
+  extern volatile bool z_probe_is_active;
+#endif
+
 #if ENABLED(SDSUPPORT)
   #include "SdFatUtil.h"
   int freeMemory() { return SdFatUtil::FreeRam(); }
     servo[3].detach();
   #endif
 
-  // Set position of Servo Endstops that are defined
-  #if HAS_SERVO_ENDSTOPS
+   #if HAS_SERVO_ENDSTOPS
+
+    z_probe_is_active = false;
+
+    /**
+     * Set position of all defined Servo Endstops
+     *
+     * ** UNSAFE! - NEEDS UPDATE! **
+     *
+     * The servo might be deployed and positioned too low to stow
+     * when starting up the machine or rebooting the board.
+     * There's no way to know where the nozzle is positioned until
+     * homing has been done - no homing with z-probe without init!
+     *
+     */
     for (int i = 0; i < 3; i++)
       if (servo_endstop_id[i] >= 0)
         servo[servo_endstop_id[i]].move(servo_endstop_angle[i][1]);
-  #endif
+
+  #endif // HAS_SERVO_ENDSTOPS
 
 }
 
     refresh_cmd_timeout();
   }
 
+  #if ENABLED(HAS_Z_MIN_PROBE)
+
   static void deploy_z_probe() {
 
     #if ENABLED(DEBUG_LEVELING_FEATURE)
       }
     #endif
 
+    if (z_probe_is_active) return;
+
     #if HAS_SERVO_ENDSTOPS
 
       // Engage Z Servo endstop if enabled
             if (Z_PROBE_ALLEN_KEY_DEPLOY_3_FEEDRATE != Z_PROBE_ALLEN_KEY_DEPLOY_2_FEEDRATE)
               feedrate = Z_PROBE_ALLEN_KEY_DEPLOY_3_FEEDRATE;
 
-          // Move to trigger deployment
-          if (Z_PROBE_ALLEN_KEY_DEPLOY_3_FEEDRATE != Z_PROBE_ALLEN_KEY_DEPLOY_2_FEEDRATE)
-            feedrate = Z_PROBE_ALLEN_KEY_DEPLOY_3_FEEDRATE;
-          if (Z_PROBE_ALLEN_KEY_DEPLOY_3_X != Z_PROBE_ALLEN_KEY_DEPLOY_2_X)
-            destination[X_AXIS] = Z_PROBE_ALLEN_KEY_DEPLOY_3_X;
-          if (Z_PROBE_ALLEN_KEY_DEPLOY_3_Y != Z_PROBE_ALLEN_KEY_DEPLOY_2_Y)
-            destination[Y_AXIS] = Z_PROBE_ALLEN_KEY_DEPLOY_3_Y;
-          if (Z_PROBE_ALLEN_KEY_DEPLOY_3_Z != Z_PROBE_ALLEN_KEY_DEPLOY_2_Z)
-            destination[Z_AXIS] = Z_PROBE_ALLEN_KEY_DEPLOY_3_Z;
-
-          prepare_move_raw();
-
-        #endif
-      }
+            // Move to trigger deployment
+            if (Z_PROBE_ALLEN_KEY_DEPLOY_3_FEEDRATE != Z_PROBE_ALLEN_KEY_DEPLOY_2_FEEDRATE)
+              feedrate = Z_PROBE_ALLEN_KEY_DEPLOY_3_FEEDRATE;
+            if (Z_PROBE_ALLEN_KEY_DEPLOY_3_X != Z_PROBE_ALLEN_KEY_DEPLOY_2_X)
+              destination[X_AXIS] = Z_PROBE_ALLEN_KEY_DEPLOY_3_X;
+            if (Z_PROBE_ALLEN_KEY_DEPLOY_3_Y != Z_PROBE_ALLEN_KEY_DEPLOY_2_Y)
+              destination[Y_AXIS] = Z_PROBE_ALLEN_KEY_DEPLOY_3_Y;
+            if (Z_PROBE_ALLEN_KEY_DEPLOY_3_Z != Z_PROBE_ALLEN_KEY_DEPLOY_2_Z)
+              destination[Z_AXIS] = Z_PROBE_ALLEN_KEY_DEPLOY_3_Z;
+
+            prepare_move_raw();
+          #endif
+        }
 
       // Partially Home X,Y for safety
       destination[X_AXIS] = destination[X_AXIS] * 0.75;
 
     #endif // Z_PROBE_ALLEN_KEY
 
+    #if ENABLED(FIX_MOUNTED_PROBE)
+      // Noting to be done. Just set z_probe_is_active
+    #endif
+
+    z_probe_is_active = true;
+
   }
 
   static void stow_z_probe(bool doRaise = true) {
       }
     #endif
 
+    if (!z_probe_is_active) return;
+
     #if HAS_SERVO_ENDSTOPS
 
       // Retract Z Servo endstop if enabled
           Stop();
         }
     #endif // Z_PROBE_ALLEN_KEY
+
+    #if ENABLED(FIX_MOUNTED_PROBE)
+      // Noting to be done. Just set z_probe_is_active
+    #endif
+
+    z_probe_is_active = false;
   }
+  #endif // HAS_Z_MIN_PROBE
 
   enum ProbeAction {
     ProbeStay          = 0,
         SERIAL_EOL;
       }
     #endif
+
+    if (z_probe_is_active == dock) return;
+
     if (!axis_known_position[X_AXIS] || !axis_known_position[Y_AXIS]) {
       LCD_MESSAGEPGM(MSG_POSITION_UNKNOWN);
       SERIAL_ECHO_START;
       digitalWrite(SLED_PIN, HIGH); // turn on magnet
     }
     do_blocking_move_to_x(oldXpos); // return to position before docking
+
+    z_probe_is_active = dock;
   }
 
 #endif // Z_PROBE_SLED
       if (axis == Z_AXIS) {
         if (axis_home_dir < 0) dock_sled(false);
       }
-    #endif
-
-    #if SERVO_LEVELING && DISABLED(Z_PROBE_SLED)
+    #elif SERVO_LEVELING || ENABLED(FIX_MOUNTED_PROBE)
 
       // Deploy a Z probe if there is one, and homing towards the bed
       if (axis == Z_AXIS) {
 
     #if HAS_SERVO_ENDSTOPS
       // Engage Servo endstop if enabled
-      if (axis != Z_AXIS && servo_endstop_id[axis] >= 0)
+      if (axis != Z_AXIS && servo_endstop_id[axis] >= 0) {
         servo[servo_endstop_id[axis]].move(servo_endstop_angle[axis][0]);
+        z_probe_is_active = true;
+      }
     #endif
 
     // Set a flag for Z motor locking
       if (axis == Z_AXIS) {
         if (axis_home_dir < 0) dock_sled(true);
       }
-    #endif
-
-    #if SERVO_LEVELING && DISABLED(Z_PROBE_SLED)
+    #elif SERVO_LEVELING || ENABLED(FIX_MOUNTED_PROBE)
 
       // Deploy a Z probe if there is one, and homing towards the bed
       if (axis == Z_AXIS) {
             }
           #endif
           servo[servo_endstop_id[axis]].move(servo_endstop_angle[axis][1]);
+          z_probe_is_active = false;
         }
       #endif
     }
       #if ENABLED(Z_PROBE_ALLEN_KEY)
         stow_z_probe();
       #elif Z_RAISE_AFTER_PROBING > 0
-        raise_z_after_probing();
+        raise_z_after_probing(); // ???
       #endif
     #else // !DELTA
       if (verbose_level > 0)
         }
       #endif
       enqueue_and_echo_commands_P(PSTR(Z_PROBE_END_SCRIPT));
+      #if ENABLED(HAS_Z_MIN_PROBE)
+        z_probe_is_active = false;
+      #endif
       st_synchronize();
     #endif
 
 
   }
 
-  #if DISABLED(Z_PROBE_SLED)
+  #if DISABLED(Z_PROBE_SLED) // could be avoided
 
     /**
      * G30: Do a single Z probe at the current XY
       #if HAS_SERVO_ENDSTOPS
         raise_z_for_servo();
       #endif
-      deploy_z_probe(); // Engage Z Servo endstop if available
+      deploy_z_probe(); // Engage Z Servo endstop if available. Z_PROBE_SLED is missed her.
 
       st_synchronize();
       // TODO: clear the leveling matrix or the planner will be set incorrectly
-      setup_for_endstop_move();
+      setup_for_endstop_move(); // to late. Must be done before deploying.
 
       feedrate = homing_feedrate[Z_AXIS];
 
       SERIAL_PROTOCOL(current_position[Z_AXIS] + 0.0001);
       SERIAL_EOL;
 
-      clean_up_after_endstop_move();
+      clean_up_after_endstop_move(); // to early. must be done after the stowing.
 
       #if HAS_SERVO_ENDSTOPS
         raise_z_for_servo();
       #endif
-      stow_z_probe(false); // Retract Z Servo endstop if available
+      stow_z_probe(false); // Retract Z Servo endstop if available. Z_PROBE_SLED is missed her.
     }
 
   #endif //!Z_PROBE_SLED

Marlin/SanityCheck.h

 #endif
 
 /**
+ * Probes
+ */
+
+  /**
+   * A probe needs a pin
+   */
+#if (!((HAS_Z_MIN && ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)) || HAS_Z_PROBE )) && ( ENABLED(FIX_MOUNTED_PROBE) || defined(Z_ENDSTOP_SERVO_NR) || ENABLED(Z_PROBE_ALLEN_KEY) || ENABLED(Z_PROBE_SLED))
+  #error A probe needs a pin! [Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN || HAS_Z_PROBE]
+#endif
+
+#if ((HAS_Z_MIN && ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN)) && HAS_Z_PROBE) && ( ENABLED(FIX_MOUNTED_PROBE) || defined(Z_ENDSTOP_SERVO_NR) || ENABLED(Z_PROBE_ALLEN_KEY) || ENABLED(Z_PROBE_SLED))
+  #error A probe should not be connected to more then one pin! [Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN || HAS_Z_PROBE]
+#endif
+
+  /**
+    * Require one kind of probe
+    */
+#if ENABLED(AUTO_BED_LEVELING_FEATURE) && !( ENABLED(FIX_MOUNTED_PROBE) || defined(Z_ENDSTOP_SERVO_NR) || ENABLED(Z_PROBE_ALLEN_KEY) || ENABLED(Z_PROBE_SLED))
+  #error For AUTO_BED_LEVELING_FEATURE define one kind of probe! {Servo | Z_PROBE_ALLEN_KEY | Z_PROBE_SLED | FIX_MOUNTED_PROBE]
+#endif
+
+#if ENABLED(Z_SAFE_HOMING)&& !( ENABLED(FIX_MOUNTED_PROBE) || defined(Z_ENDSTOP_SERVO_NR) || ENABLED(Z_PROBE_ALLEN_KEY) || ENABLED(Z_PROBE_SLED))
+  #error For Z_SAFE_HOMING define one kind of probe! {Servo | Z_PROBE_ALLEN_KEY | Z_PROBE_SLED | FIX_MOUNTED_PROBE]
+#endif
+
+// To do: Fail with more then one probe defined
+
+/**
  * Auto Bed Leveling
  */
 #if ENABLED(AUTO_BED_LEVELING_FEATURE)

Marlin/example_configurations/Felix/Configuration.h

 #define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/Felix/Configuration_DUAL.h

 #define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/Hephestos/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/Hephestos_2/Configuration.h

 #define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/K8200/Configuration.h

 #define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/RepRapWorld/Megatronics/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/RigidBot/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/SCARA/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  //#define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  //#define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                            // This feature is meant to avoid Z homing with Z probe outside the bed area.
                             // When defined, it will:
                             // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                             // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/TAZ4/Configuration.h

 #define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.

Marlin/example_configurations/WITBOX/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/adafruit/ST7565/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/delta/biv2.5/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 #define DISABLE_MIN_ENDSTOPS // Deltas only use min endstops for probing.
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/delta/generic/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 #define DISABLE_MIN_ENDSTOPS // Deltas only use min endstops for probing.
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+//#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/delta/kossel_mini/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS // Deltas only use min endstops for probing.
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/delta/kossel_pro/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS // Deltas only use min endstops for probing.
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/delta/kossel_xl/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
 //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                             // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/makibox/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/example_configurations/tvrrug/Round2/Configuration.h

 //#define DISABLE_MAX_ENDSTOPS
 //#define DISABLE_MIN_ENDSTOPS
 
+//===========================================================================
+//============================= Z Probe Options =============================
+//===========================================================================
+
+// Enable Z_MIN_PROBE_ENDSTOP to use _both_ a Z-probe and a Z-min-endstop on the same machine.
+// With this option the Z_MIN_PROBE_PIN will only be used for probing, never for homing.
+//
+// *** PLEASE READ ALL INSTRUCTIONS BELOW FOR SAFETY! ***
+//
+// To continue using the Z-min-endstop for homing, be sure to disable Z_SAFE_HOMING.
+// Example: To park the head outside the bed area when homing with G28.
+//
+// To use a separate Z probe, your board must define a Z_MIN_PROBE_PIN.
+//
+// For a servo-based Z probe, you must set up servo support below, including
+// NUM_SERVOS, Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES.
+//
+// - RAMPS 1.3/1.4 boards may be able to use the 5V, GND, and Aux4->D32 pin.
+// - Use 5V for powered (usu. inductive) sensors.
+// - Otherwise connect:
+//   - normally-closed switches to GND and D32.
+//   - normally-open switches to 5V and D32.
+//
+// Normally-closed switches are advised and are the default.
+//
+// The Z_MIN_PROBE_PIN sets the Arduino pin to use. (See your board's pins file.)
+// Since the RAMPS Aux4->D32 pin maps directly to the Arduino D32 pin, D32 is the
+// default pin for all RAMPS-based boards. Some other boards map differently.
+// To set or change the pin for your board, edit the appropriate pins_XXXXX.h file.
+//
+// WARNING:
+// Setting the wrong pin may have unexpected and potentially disastrous consequences.
+// Use with caution and do your homework.
+//
+//#define Z_MIN_PROBE_ENDSTOP
+
+// If you want to use the Z_MIN_PIN to connect your Z_MIN_PROBE comment out the next define.
+// In other words. The z-min-probe is connected to the Z_MIN_PIN and is used for homing and for probing.
+#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN
+// If you want to use a probe you do have to define one of the two defines above!
+
 // If you want to enable the Z probe pin, but disable its use, uncomment the line below.
 // This only affects a Z probe endstop if you have separate Z min endstop as well and have
-// activated Z_MIN_PROBE_ENDSTOP below. If you are using the Z Min endstop on your Z probe,
+// activated Z_MIN_PROBE_ENDSTOP above. If you are using the Z Min endstop on your Z probe,
 // this has no effect.
+// In other words. If a Z_MIN_PROBE_PIN is defined in your pin file - don't use it.
 //#define DISABLE_Z_MIN_PROBE_ENDSTOP
 
 // For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
   //#define Z_PROBE_END_SCRIPT "G1 Z10 F12000\nG1 X15 Y330\nG1 Z0.5\nG1 Z10" // These commands will be executed in the end of G29 routine.
                                                                              // Useful to retract a deployable Z probe.
 
+  // Probes are sensors/switches that need to be activated before they can be used
+  // and deactivated after the use.
+  // Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, ... . You have to activate one of these for the AUTO_BED_LEVELING_FEATURE
+
+  // A fix mounted probe, like the normal inductive probe, must be deactivated to go below Z_PROBE_OFFSET_FROM_EXTRUDER
+  // when the hardware endstops are active.
+  //#define FIX_MOUNTED_PROBE
+
+  // A Servo Probe can be defined in the servo section below.
+
+  // A Allen Key Probe is currently predefined only in the delta example configurations.
+
   //#define Z_PROBE_SLED // Turn on if you have a Z probe mounted on a sled like those designed by Charles Bell.
   //#define SLED_DOCKING_OFFSET 5 // The extra distance the X axis must travel to pickup the sled. 0 should be fine but you can push it further if you'd like.
 
   //If you have enabled the Bed Auto Leveling and are using the same Z Probe for Z Homing,
   //it is highly recommended you let this Z_SAFE_HOMING enabled!!!
 
-  #define Z_SAFE_HOMING   // This feature is meant to avoid Z homing with Z probe outside the bed area.
+  #define Z_SAFE_HOMING   // Use the z-min-probe for homing to z-min - not the z-min-endstop.
+                          // This feature is meant to avoid Z homing with Z probe outside the bed area.
                           // When defined, it will:
                           // - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
                           // - If stepper drivers timeout, it will need X and Y homing again before Z homing.
 
   #endif
 
-  // Support for a dedicated Z probe endstop separate from the Z min endstop.
-  // If you would like to use both a Z probe and a Z min endstop together,
-  // uncomment #define Z_MIN_PROBE_ENDSTOP and read the instructions below.
-  // If you still want to use the Z min endstop for homing, disable Z_SAFE_HOMING above.
-  // Example: To park the head outside the bed area when homing with G28.
-  //
-  // WARNING:
-  // The Z min endstop will need to set properly as it would without a Z probe
-  // to prevent head crashes and premature stopping during a print.
-  //
-  // To use a separate Z probe endstop, you must have a Z_MIN_PROBE_PIN
-  // defined in the pins_XXXXX.h file for your control board.
-  // If you are using a servo based Z probe, you will need to enable NUM_SERVOS,
-  // Z_ENDSTOP_SERVO_NR and SERVO_ENDSTOP_ANGLES in the R/C SERVO support below.
-  // RAMPS 1.3/1.4 boards may be able to use the 5V, Ground and the D32 pin
-  // in the Aux 4 section of the RAMPS board. Use 5V for powered sensors,
-  // otherwise connect to ground and D32 for normally closed configuration
-  // and 5V and D32 for normally open configurations.
-  // Normally closed configuration is advised and assumed.
-  // The D32 pin in Aux 4 on RAMPS maps to the Arduino D32 pin.
-  // Z_MIN_PROBE_PIN is setting the pin to use on the Arduino.
-  // Since the D32 pin on the RAMPS maps to D32 on Arduino, this works.
-  // D32 is currently selected in the RAMPS 1.3/1.4 pin file.
-  // All other boards will need changes to the respective pins_XXXXX.h file.
-  //
-  // WARNING:
-  // Setting the wrong pin may have unexpected and potentially disastrous outcomes.
-  // Use with caution and do your homework.
-  //
-  //#define Z_MIN_PROBE_ENDSTOP
-
 #endif // AUTO_BED_LEVELING_FEATURE
 
 

Marlin/stepper.cpp

 //===========================================================================
 block_t* current_block;  // A pointer to the block currently being traced
 
+#if ENABLED(HAS_Z_MIN_PROBE)
+  volatile bool z_probe_is_active = false;
+#endif
 
 //===========================================================================
 //============================= private variables ===========================
             }
           #else // !Z_DUAL_ENDSTOPS
 
-            UPDATE_ENDSTOP(Z, MIN);
-
+            #if ENABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN) && ENABLED(HAS_Z_MIN_PROBE)
+              if (z_probe_is_active) UPDATE_ENDSTOP(Z, MIN);
+            #else
+              UPDATE_ENDSTOP(Z, MIN);
+            #endif
           #endif // !Z_DUAL_ENDSTOPS
-        #endif // Z_MIN_PIN
-
-        #if ENABLED(Z_MIN_PROBE_ENDSTOP)
-          UPDATE_ENDSTOP(Z, MIN_PROBE);
+        #endif
 
-          if (TEST_ENDSTOP(Z_MIN_PROBE)) {
-            endstops_trigsteps[Z_AXIS] = count_position[Z_AXIS];
-            SBI(endstop_hit_bits, Z_MIN_PROBE);
+        #if ENABLED(Z_MIN_PROBE_ENDSTOP) && DISABLED(Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN) && ENABLED(HAS_Z_MIN_PROBE)
+          if (z_probe_is_active) {
+            UPDATE_ENDSTOP(Z, MIN_PROBE);
+            if (TEST_ENDSTOP(Z_MIN_PROBE)) endstop_hit_bits |= _BV(Z_MIN_PROBE);
           }
         #endif
       }
   if (current_block != NULL) {
 
     // Update endstops state, if enabled
-    if (check_endstops) update_endstops();
+    #if ENABLED(HAS_Z_MIN_PROBE)
+      if (check_endstops || z_probe_is_active) update_endstops();
+    #else
+      if (check_endstops) update_endstops();
+    #endif
 
     // Take multiple steps per interrupt (For high speed moves)
     for (int8_t i = 0; i < step_loops; i++) {