What command to send over UART for emergency stop?

[Autocrit]

I have a pendant connected to an Arduino (Sparkfun Pro Micro - basically the Duet3D CNC Pendant project with modified firmware), and on to a UART port on a BTT Scylla.

grblHAL is compiled with MPG_ENABLE 2 and MPG_STREAM 2.

Jog commands in the form of gcode work and I hoped that 0x19 would work for the emergency stop button, putting grblHAL into an alarm state but all I see is [MSG:Stop] in the console.

This is a bit of test code for Arduino IDE:

#define CMD_STOP 0x19

void setup() {
  Serial1.begin(115200);
}

void loop() {
  unsigned long now = millis();
  static unsigned long start = now;

  // Send stop command every 10 seconds
  if((now - start) >= 10000) {
    Serial1.write(CMD_STOP);
    start = now;
  }
}

[terjeio]

Use CMD_RESET (0x18).

[Autocrit]

0x18 resets the controller but no alarm or e-stop behaviour

[terjeio]

Alarm is only raised on CMD_RESET if in motion, there is no real-time command that resets and then sets the estop state.

[petervanderwalt]

(: that could be useful new command though - even from plugins that need to call en e-stop (Temp sensor on ATC spindle for example?)

…

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[terjeio]

Plugins that needs the controller to enter estop mode can call hal.control.interrupt_callback() with the e_stop signal set.
If to be set via a real-time command two are needed, one to set and one to clear the condition? And overriding the estop button when set?

[Autocrit]

For this pendant e-stop and restart after e-stop would be good

[terjeio]

Added as 0x9F - though I am not convinced this is a good idea...
Note that only alarm 10 is reported, not the complementary e-stop message since that is misleading.

[Autocrit]

Thank you