A
Dear @579-Peter
1, M140 S0 means the temperature of the hot bed is set to 0 degrees Celsius, which makes the machine can not complete this command, so it has been hanging there, because the machine does not have a cooling function, can not make the temperature of the hot bed to 0 degrees Celsius, please set the temperature to room temperature or 26 degrees Celsius or 30 degrees Celsius
2, can not disable 5VDC through the serial port