remove config

Marlin/Marlin_main.cpp

 static millis_t stepper_inactive_time = DEFAULT_STEPPER_DEACTIVE_TIME * 1000L;
 millis_t print_job_start_ms = 0; ///< Print job start time
 millis_t print_job_stop_ms = 0;  ///< Print job stop time
+static millis_t last_command_time = 0;
 static uint8_t target_extruder;
 bool no_wait_for_cooling = true;
 bool target_direction;
 
   if (drain_queued_commands_P()) return; // priority is given to non-serial commands
   
+  millis_t ms = millis();
+  
+  if (!MYSERIAL.available() && commands_in_queue == 0 && ms - last_command_time > 1000) {
+    SERIAL_ECHOLNPGM(MSG_WAIT);
+    last_command_time = ms;
+  }
+  
   while (MYSERIAL.available() > 0 && commands_in_queue < BUFSIZE) {
-
+    last_command_time = ms;
     serial_char = MYSERIAL.read();
 
     if (serial_char == '\n' || serial_char == '\r' ||

Marlin/language.h

 #define MSG_FREE_MEMORY                     " Free Memory: "
 #define MSG_PLANNER_BUFFER_BYTES            "  PlannerBufferBytes: "
 #define MSG_OK                              "ok"
+#define MSG_WAIT                            "wait"
 #define MSG_FILE_SAVED                      "Done saving file."
 #define MSG_ERR_LINE_NO                     "Line Number is not Last Line Number+1, Last Line: "
 #define MSG_ERR_CHECKSUM_MISMATCH           "checksum mismatch, Last Line: "