M408 does not respond when sensing endstops



  • M408 does not respond when sensing endstops. What is preventing the response?


  • administrators

    @ct said in M408 does not respond when sensing endstops:

    M408 does not respond when sensing endstops. What is preventing the response?

    Please explain what you mean in more detail.



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  • @dc42 If I send a M408 from the web interface ‘Send’ button during a move without sensing endpoint it responds with the status. If I send it with sensing endpoint it buffers the responses and sends them all at the end of the move. M408 sent using RS232 responds immediately regardless of whether sensing endpoint is on or off. The discrepancies threw me during testing but it doesn’t cause me a problem as I am using the comm port. I'm sorry if I have wasted your time.


  • administrators

    The reason is that each GCode input channel can only process one command at a time. Ordinary movement commands are placed in a queue for later execution, so unless the queue is full, processing them happens immediately. But when a homing move is executed, the system has to wait until it completes so that the axis positions can be reset. So processing it doesn't finish until the move does.

    The same applies to all input channels. So if you initiate a homing move from DWC, you can execute M408 and other non-motion commands concurrently from serial; and vice versa.

    HTH David


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