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M571: Set output on extrude
- Snnn Output value
- Fnnn Output PWM frequency (RepRapFirmware 1.17 and later; deprecated in 3.2beta2 and later)
- Qnnn Output PWM frequency (RepRapFirmware 3.2beta2 and later)
- Pnnn [RepRapFirmware 1 and 2] Logical pin number (RepRapFirmware 1.17), defaults to the FAN0 output in firmware 1.19 and earlier until M571 with a P parameter has been seen
- P"pin-name" [RepRapFirmware 3] Name of the pin to use
- M571 P3 F200 S1 ; turn on logical pin 3 while extrusion is commanded (RRF 2)
- M571 P"heater3" S0.5 ; turn on heater 3 output at 50% PWM while extrusion is commanded (RRF 3)
This turns the controlled pin output on whenever extrusion is being done, and turns it off when the extrusion is finished. The output could control a fan or a stirrer or anything else that needs to work just when extrusion is happening. It also can be used to control a laser beam. The S parameter sets the value of the PWM to the output. 0.0 is off; 1.0 is fully on.
In RepRapFirmware 1.17 and later you can use the P parameter to change the pin used and you can also set the PWM frequency. For RepRapFirmware 1.x and 2.x, pin numbers are the same as in the M42 and M280 commands. The pin you specify must not be in use for anything else, so if it is normally used as a heater you must disable the heater first using M307, or if it is used for a fan you must disable the fan using M106 with the I-1 parameter. In RepRapFirmware 3 you specify the pin name instead.
RepRapFirmware 1.20 and later do not default to using the FAN0 output, so you must send M571 with a P parameter at least once to define the pin that you wish to use.