More redundant temp sensor changes. (After testing and debugging by reifsnderb)

Marlin/Configuration.h

 #define TEMP_SENSOR_BED 0
 
 // This makes temp sensor 1 a redundant sensor for sensor 0. If the temperatures difference between these sensors is to high the print will be aborted.
-#define TEMP_SENSOR_1_AS_REDUNDANT 
-#define MAX_REDUNDANT_TEMP_SENSOR_DIFF 5
+//#define TEMP_SENSOR_1_AS_REDUNDANT 
+#define MAX_REDUNDANT_TEMP_SENSOR_DIFF 10
 
 // Actual temperature must be close to target for this long before M109 returns success
 #define TEMP_RESIDENCY_TIME 10  // (seconds)

Marlin/Configuration_adv.h

 //===========================================================================
 //=============================  Define Defines  ============================
 //===========================================================================
+#if EXTRUDERS > 1 && defined TEMP_SENSOR_1_AS_REDUNDANT
+  #error "You cannot use  TEMP_SENSOR_1_AS_REDUNDANT if EXTRUDERS > 1"
+#endif
 
 #if TEMP_SENSOR_0 > 0
   #define THERMISTORHEATER_0 TEMP_SENSOR_0
   #undef BED_MAXTEMP
 #endif
 
-#if EXTRUDERS > 1 && defined TEMP_SENSOR_1_AS_REDUNDANT
-  #error "You cannot use  TEMP_SENSOR_1_AS_REDUNDANT if EXTRUDERS > 1"
-#endif
 
 #endif //__CONFIGURATION_ADV_H

Marlin/Marlin_main.cpp

     case 105 : // M105
       if(setTargetedHotend(105)){
         break;
-      }
+        }
       #if defined(TEMP_0_PIN) && TEMP_0_PIN > -1
         SERIAL_PROTOCOLPGM("ok T:");
         SERIAL_PROTOCOL_F(degHotend(tmp_extruder),1);
     }
   }
   return false;
-}
+}

Marlin/pins.h

 
 #if MOTHERBOARD == 33 || MOTHERBOARD == 34
 
-#define LARGE_FLASH        true
+  #define LARGE_FLASH        true
+
+  #define X_STEP_PIN         54
+  #define X_DIR_PIN          55
+  #define X_ENABLE_PIN       38
+  #define X_MIN_PIN           3
+  #define X_MAX_PIN           2
+
+  #define Y_STEP_PIN         60
+  #define Y_DIR_PIN          61
+  #define Y_ENABLE_PIN       56
+  #define Y_MIN_PIN          14
+  #define Y_MAX_PIN          15
+
+  #define Z_STEP_PIN         46
+  #define Z_DIR_PIN          48
+  #define Z_ENABLE_PIN       62
+  #define Z_MIN_PIN          18
+  #define Z_MAX_PIN          19
+
+  #define Z2_STEP_PIN        36
+  #define Z2_DIR_PIN         34
+  #define Z2_ENABLE_PIN      30
+
+  #define E0_STEP_PIN        26
+  #define E0_DIR_PIN         28
+  #define E0_ENABLE_PIN      24
+
+  #define E1_STEP_PIN        36
+  #define E1_DIR_PIN         34
+  #define E1_ENABLE_PIN      30
+
+  #define SDPOWER            -1
+  #define SDSS               53
+  #define LED_PIN            13
+
+  #if MOTHERBOARD == 33
+    #define FAN_PIN            9 // (Sprinter config)
+  #else
+    #define FAN_PIN            4 // IO pin. Buffer needed
+  #endif
 
-#define X_STEP_PIN         54
-#define X_DIR_PIN          55
-#define X_ENABLE_PIN       38
-#define X_MIN_PIN           3
-#define X_MAX_PIN           2
+  #define PS_ON_PIN          12
 
-#define Y_STEP_PIN         60
-#define Y_DIR_PIN          61
-#define Y_ENABLE_PIN       56
-#define Y_MIN_PIN          14
-#define Y_MAX_PIN          15
+  #if defined(REPRAP_DISCOUNT_SMART_CONTROLLER) || defined(G3D_PANEL)
+    #define KILL_PIN           41
+  #else
+    #define KILL_PIN           -1
+  #endif
 
-#define Z_STEP_PIN         46
-#define Z_DIR_PIN          48
-#define Z_ENABLE_PIN       62
-#define Z_MIN_PIN          18
-#define Z_MAX_PIN          19
+  #define HEATER_0_PIN       10   // EXTRUDER 1
 
-#define Z2_STEP_PIN        36
-#define Z2_DIR_PIN         34
-#define Z2_ENABLE_PIN      30
+  #if MOTHERBOARD == 33
+    #define HEATER_1_PIN       -1
+  #else
+    #define HEATER_1_PIN       9    // EXTRUDER 2 (FAN On Sprinter)
+  #endif
 
-#define E0_STEP_PIN        26
-#define E0_DIR_PIN         28
-#define E0_ENABLE_PIN      24
+  #define HEATER_2_PIN       -1
+  #define TEMP_0_PIN         13   // ANALOG NUMBERING
+  #define TEMP_1_PIN         15   // ANALOG NUMBERING
+  #define TEMP_2_PIN         -1   // ANALOG NUMBERING
+  #define HEATER_BED_PIN     8    // BED
+  #define TEMP_BED_PIN       14   // ANALOG NUMBERING
 
-#define E1_STEP_PIN        36
-#define E1_DIR_PIN         34
-#define E1_ENABLE_PIN      30
 
-#define SDPOWER            -1
-#define SDSS               53
-#define LED_PIN            13
 
-#if MOTHERBOARD == 33
-#define FAN_PIN            9 // (Sprinter config)
-#else
-#define FAN_PIN            4 // IO pin. Buffer needed
-#endif
-#define PS_ON_PIN          12
+  #ifdef NUM_SERVOS
+    #define SERVO0_PIN         11
 
-#if defined(REPRAP_DISCOUNT_SMART_CONTROLLER) || defined(G3D_PANEL)
-#define KILL_PIN           41
-#else
-#define KILL_PIN           -1
-#endif
+    #if NUM_SERVOS > 1
+      #define SERVO1_PIN         6
+    #endif
 
-#define HEATER_0_PIN       10   // EXTRUDER 1
-#if MOTHERBOARD == 33
-#define HEATER_1_PIN       -1
-#else
-#define HEATER_1_PIN       9    // EXTRUDER 2 (FAN On Sprinter)
-#endif
-#define HEATER_2_PIN       -1
-#define TEMP_0_PIN         13   // ANALOG NUMBERING
-#define TEMP_1_PIN         15   // ANALOG NUMBERING
-#define TEMP_2_PIN         -1   // ANALOG NUMBERING
-#define HEATER_BED_PIN     8    // BED
-#define TEMP_BED_PIN       14   // ANALOG NUMBERING
+    #if NUM_SERVOS > 2
+      #define SERVO2_PIN         5
+    #endif
 
-#ifdef NUM_SERVOS
-  #define SERVO0_PIN         11
-  #if NUM_SERVOS > 1
-  #define SERVO1_PIN         6
-  #endif
-  #if NUM_SERVOS > 2
-  #define SERVO2_PIN         5
-  #endif
-  #if NUM_SERVOS > 2
-  #define SERVO3_PIN         4
+    #if NUM_SERVOS > 2
+      #define SERVO3_PIN         4
+    #endif
   #endif
-#endif
 
-#ifdef ULTRA_LCD
+  #ifdef ULTRA_LCD
 
-  #ifdef NEWPANEL
-    #define LCD_PINS_RS 16 
-    #define LCD_PINS_ENABLE 17
-    #define LCD_PINS_D4 23
-    #define LCD_PINS_D5 25
-    #define LCD_PINS_D6 27
-    #define LCD_PINS_D7 29
-
-    #ifdef REPRAP_DISCOUNT_SMART_CONTROLLER
-      #define BEEPER 37
+    #ifdef NEWPANEL
+      #define LCD_PINS_RS 16 
+      #define LCD_PINS_ENABLE 17
+      #define LCD_PINS_D4 23
+      #define LCD_PINS_D5 25
+      #define LCD_PINS_D6 27
+      #define LCD_PINS_D7 29
 
-      #define BTN_EN1 31
-      #define BTN_EN2 33
-      #define BTN_ENC 35
+      #ifdef REPRAP_DISCOUNT_SMART_CONTROLLER
+        #define BEEPER 37
 
-      #define SDCARDDETECT 49
-    #else
-      //arduino pin which triggers an piezzo beeper
-      #define BEEPER 33  // Beeper on AUX-4
-
-      //buttons are directly attached using AUX-2
-      #ifdef REPRAPWORLD_KEYPAD
-        #define BTN_EN1 64 // encoder
-        #define BTN_EN2 59 // encoder
-        #define BTN_ENC 63 // enter button
-        #define SHIFT_OUT 40 // shift register
-        #define SHIFT_CLK 44 // shift register
-        #define SHIFT_LD 42 // shift register
-      #else
-        #define BTN_EN1 37
-        #define BTN_EN2 35
-        #define BTN_ENC 31  //the click
-      #endif
+        #define BTN_EN1 31
+        #define BTN_EN2 33
+        #define BTN_ENC 35
 
-      #ifdef G3D_PANEL
         #define SDCARDDETECT 49
       #else
-        #define SDCARDDETECT -1  // Ramps does not use this port
+        //arduino pin which triggers an piezzo beeper
+        #define BEEPER 33  // Beeper on AUX-4
+
+        //buttons are directly attached using AUX-2
+        #ifdef REPRAPWORLD_KEYPAD
+          #define BTN_EN1 64 // encoder
+          #define BTN_EN2 59 // encoder
+          #define BTN_ENC 63 // enter button
+          #define SHIFT_OUT 40 // shift register
+          #define SHIFT_CLK 44 // shift register
+          #define SHIFT_LD 42 // shift register
+        #else
+          #define BTN_EN1 37
+          #define BTN_EN2 35
+          #define BTN_ENC 31  //the click
+        #endif
+
+        #ifdef G3D_PANEL
+          #define SDCARDDETECT 49
+        #else
+          #define SDCARDDETECT -1  // Ramps does not use this port
+        #endif
+    
       #endif
-    #endif
 
-  #else //old style panel with shift register
-    //arduino pin witch triggers an piezzo beeper
-    #define BEEPER 33   // No Beeper added 
-
-    //buttons are attached to a shift register
-  // Not wired this yet
-    //#define SHIFT_CLK 38
-    //#define SHIFT_LD 42
-    //#define SHIFT_OUT 40
-    //#define SHIFT_EN 17
-
-    #define LCD_PINS_RS 16
-    #define LCD_PINS_ENABLE 17
-    #define LCD_PINS_D4 23
-    #define LCD_PINS_D5 25
-    #define LCD_PINS_D6 27
-    #define LCD_PINS_D7 29
-  #endif 
-#endif //ULTRA_LCD
+    #else //old style panel with shift register
+      //arduino pin witch triggers an piezzo beeper
+      #define BEEPER 33   // No Beeper added 
+
+      //buttons are attached to a shift register
+      // Not wired this yet
+      //#define SHIFT_CLK 38
+      //#define SHIFT_LD 42
+      //#define SHIFT_OUT 40
+      //#define SHIFT_EN 17
+
+      #define LCD_PINS_RS 16
+      #define LCD_PINS_ENABLE 17
+      #define LCD_PINS_D4 23
+      #define LCD_PINS_D5 25
+      #define LCD_PINS_D6 27
+      #define LCD_PINS_D7 29
+    #endif 
+  #endif //ULTRA_LCD
 
 #else // RAMPS_V_1_1 or RAMPS_V_1_2 as default (MOTHERBOARD == 3)
 
-#define X_STEP_PIN         26
-#define X_DIR_PIN          28
-#define X_ENABLE_PIN       24
-#define X_MIN_PIN           3
-#define X_MAX_PIN          -1    //2
-
-#define Y_STEP_PIN         38
-#define Y_DIR_PIN          40
-#define Y_ENABLE_PIN       36
-#define Y_MIN_PIN          16
-#define Y_MAX_PIN          -1    //17
-
-#define Z_STEP_PIN         44
-#define Z_DIR_PIN          46
-#define Z_ENABLE_PIN       42
-#define Z_MIN_PIN          18
-#define Z_MAX_PIN          -1    //19
+  #define X_STEP_PIN         26
+  #define X_DIR_PIN          28
+  #define X_ENABLE_PIN       24
+  #define X_MIN_PIN           3
+  #define X_MAX_PIN          -1    //2
+
+  #define Y_STEP_PIN         38
+  #define Y_DIR_PIN          40
+  #define Y_ENABLE_PIN       36
+  #define Y_MIN_PIN          16
+  #define Y_MAX_PIN          -1    //17
+
+  #define Z_STEP_PIN         44
+  #define Z_DIR_PIN          46
+  #define Z_ENABLE_PIN       42
+  #define Z_MIN_PIN          18
+  #define Z_MAX_PIN          -1    //19
+
+  #define E0_STEP_PIN         32
+  #define E0_DIR_PIN          34
+  #define E0_ENABLE_PIN       30
+
+  #define SDPOWER            48
+  #define SDSS               53
+  #define LED_PIN            13
+  #define PS_ON_PIN          -1
+  #define KILL_PIN           -1
+
+  #ifdef RAMPS_V_1_0 // RAMPS_V_1_0
+    #define HEATER_0_PIN     12    // RAMPS 1.0
+    #define HEATER_BED_PIN   -1    // RAMPS 1.0
+    #define FAN_PIN          11    // RAMPS 1.0
+  #else // RAMPS_V_1_1 or RAMPS_V_1_2
+    #define HEATER_0_PIN     10    // RAMPS 1.1
+    #define HEATER_BED_PIN    8    // RAMPS 1.1
+    #define FAN_PIN           9    // RAMPS 1.1
+  #endif
 
-#define E0_STEP_PIN         32
-#define E0_DIR_PIN          34
-#define E0_ENABLE_PIN       30
+  #define HEATER_1_PIN        -1
+  #define HEATER_2_PIN        -1
+  #define TEMP_0_PIN          2    // MUST USE ANALOG INPUT NUMBERING NOT DIGITAL OUTPUT NUMBERING!!!!!!!!!
+  #define TEMP_1_PIN          -1
+  #define TEMP_2_PIN          -1
+  #define TEMP_BED_PIN        1    // MUST USE ANALOG INPUT NUMBERING NOT DIGITAL OUTPUT NUMBERING!!!!!!!!!
 
-#define SDPOWER            48
-#define SDSS               53
-#define LED_PIN            13
-#define PS_ON_PIN          -1
-#define KILL_PIN           -1
-
-#ifdef RAMPS_V_1_0 // RAMPS_V_1_0
-  #define HEATER_0_PIN     12    // RAMPS 1.0
-  #define HEATER_BED_PIN   -1    // RAMPS 1.0
-  #define FAN_PIN          11    // RAMPS 1.0
-#else // RAMPS_V_1_1 or RAMPS_V_1_2
-  #define HEATER_0_PIN     10    // RAMPS 1.1
-  #define HEATER_BED_PIN    8    // RAMPS 1.1
-  #define FAN_PIN           9    // RAMPS 1.1
-#endif
-#define HEATER_1_PIN        -1
-#define HEATER_2_PIN        -1
-#define TEMP_0_PIN          2    // MUST USE ANALOG INPUT NUMBERING NOT DIGITAL OUTPUT NUMBERING!!!!!!!!!
-#define TEMP_1_PIN          -1
-#define TEMP_2_PIN          -1
-#define TEMP_BED_PIN        1    // MUST USE ANALOG INPUT NUMBERING NOT DIGITAL OUTPUT NUMBERING!!!!!!!!!
 #endif// MOTHERBOARD == 33 || MOTHERBOARD == 34
 
 // SPI for Max6675 Thermocouple
                         HEATER_BED_PIN, FAN_PIN,                  \
                         _E0_PINS _E1_PINS _E2_PINS             \
                         analogInputToDigitalPin(TEMP_0_PIN), analogInputToDigitalPin(TEMP_1_PIN), analogInputToDigitalPin(TEMP_2_PIN), analogInputToDigitalPin(TEMP_BED_PIN) }
-#endif
+#endif

Marlin/temperature.cpp

     (defined(EXTRUDER_2_AUTO_FAN_PIN) && EXTRUDER_2_AUTO_FAN_PIN > -1)
   static unsigned long extruder_autofan_last_check;
 #endif  
-  
+
 #if EXTRUDERS > 3
-# error Unsupported number of extruders
+  # error Unsupported number of extruders
 #elif EXTRUDERS > 2
-# define ARRAY_BY_EXTRUDERS(v1, v2, v3) { v1, v2, v3 }
+  # define ARRAY_BY_EXTRUDERS(v1, v2, v3) { v1, v2, v3 }
 #elif EXTRUDERS > 1
-# define ARRAY_BY_EXTRUDERS(v1, v2, v3) { v1, v2 }
+  # define ARRAY_BY_EXTRUDERS(v1, v2, v3) { v1, v2 }
 #else
-# define ARRAY_BY_EXTRUDERS(v1, v2, v3) { v1 }
+  # define ARRAY_BY_EXTRUDERS(v1, v2, v3) { v1 }
 #endif
 
 // Init min and max temp with extreme values to prevent false errors during startup
 #ifdef BED_MAXTEMP
 static int bed_maxttemp_raw = HEATER_BED_RAW_HI_TEMP;
 #endif
-static void *heater_ttbl_map[EXTRUDERS] = ARRAY_BY_EXTRUDERS( (void *)HEATER_0_TEMPTABLE, (void *)HEATER_1_TEMPTABLE, (void *)HEATER_2_TEMPTABLE );
-static uint8_t heater_ttbllen_map[EXTRUDERS] = ARRAY_BY_EXTRUDERS( HEATER_0_TEMPTABLE_LEN, HEATER_1_TEMPTABLE_LEN, HEATER_2_TEMPTABLE_LEN );
+
+#ifdef TEMP_SENSOR_1_AS_REDUNDANT
+  static void *heater_ttbl_map[2] = {(void *)HEATER_0_TEMPTABLE, (void *)HEATER_1_TEMPTABLE };
+  static uint8_t heater_ttbllen_map[2] = { HEATER_0_TEMPTABLE_LEN, HEATER_1_TEMPTABLE_LEN };
+#else
+  static void *heater_ttbl_map[EXTRUDERS] = ARRAY_BY_EXTRUDERS( (void *)HEATER_0_TEMPTABLE, (void *)HEATER_1_TEMPTABLE, (void *)HEATER_2_TEMPTABLE );
+  static uint8_t heater_ttbllen_map[EXTRUDERS] = ARRAY_BY_EXTRUDERS( HEATER_0_TEMPTABLE_LEN, HEATER_1_TEMPTABLE_LEN, HEATER_2_TEMPTABLE_LEN );
+#endif
 
 static float analog2temp(int raw, uint8_t e);
 static float analog2tempBed(int raw);
     }
     #endif
     #ifdef TEMP_SENSOR_1_AS_REDUNDANT
-      if(fabs(current_temperature[1] - redundant_temperature) > MAX_REDUNDANT_TEMP_SENSOR_DIFF) {
+      if(fabs(current_temperature[0] - redundant_temperature) > MAX_REDUNDANT_TEMP_SENSOR_DIFF) {
         disable_heater();
         if(IsStopped() == false) {
           SERIAL_ERROR_START;
-          SERIAL_ERRORLNPGM("Extruder switched off. Temperature difference between temp sensors is to high !");
+          SERIAL_ERRORLNPGM("Extruder switched off. Temperature difference between temp sensors is too high !");
           LCD_ALERTMESSAGEPGM("Err: REDUNDANT TEMP ERROR");
         }
         #ifndef BOGUS_TEMPERATURE_FAILSAFE_OVERRIDE
 // Derived from RepRap FiveD extruder::getTemperature()
 // For hot end temperature measurement.
 static float analog2temp(int raw, uint8_t e) {
+#ifdef TEMP_SENSOR_1_AS_REDUNDANT
+  if(e > EXTRUDERS)
+#else
   if(e >= EXTRUDERS)
+#endif
   {
       SERIAL_ERROR_START;
       SERIAL_ERROR((int)e);
     }
     current_temperature_bed = analog2tempBed(current_temperature_bed_raw);
     #ifdef TEMP_SENSOR_1_AS_REDUNDANT
-      redundant_temperature =analog2temp(redundant_temperature_raw, 1);
+      redundant_temperature = analog2temp(redundant_temperature_raw, 1);
     #endif
     //Reset the watchdog after we know we have a temperature measurement.
     watchdog_reset();