Aux Comms Issue



  • I have upgraded my H-bot 3D printer with a Maestro and am very pleased with the quieter and faster printing.

    However, I am trying to use the Aux serial comms port (Panel Due connector) and whilst I can send control messages and see the printer respond (e.g. turn heater bed on, zero and move axes) I don’t receive any replies on the aux TX line in response to M105 or any other command.

    To try to diagnose the fault I have:

    a) put M575 P1 B57600 S0 in config.g to turn off checksum checking (although I am sending both a line number and checksum) but this has made no difference.

    b) run M111 P3 S1 via the USB serial and can see that the G-code interpreter is receiving commands from the aux port, including M105.

    c) Sent M105 via the USB port and confirmed the board responds with the correct revertive containing the temperatures,

    d) checked the Duet RX line with my scope and can see 3.3V logic level signals that my scope decodes as the correct ascii character sequence from my controller;

    e) checked the Duet TX line with my scope but just see a static 3.3V level. Note, this was checked both with and without my controller connected to the TX line, in case it was loading the TX line.

    Any suggestions as to what I have missed would be gratefully received?

    Perhaps there is a hardware fault on the TX line?

    Thank you,

    John


  • administrators

    The aux port defaults to operating in PanelDue mode. This means that you get the reply to a command, need to send a M408 command and look for the "seq" and "msg" fields in the response.

    I have it on the work list for RRF3 to allow it to be switched to raw mode using another M575 parameter.



  • Thanks very much for the reply which explains things.

    I was just about to reply with:

    When “M117 Hello World” is sent via web control (or USB) the aux serial TX line emits

    {“message”:”HELLO WORLD”}/n

    and this is received and correctly displayed by my controller. So, it looks as though the TX line hardware is working.

    Then tried sending M408 S0 and received a sensible JSON response.

    Also found that M20 gives no response, whereas M20 S2 yields sensible JSON.

    So, it looks as though via the Aux channel, the Maestro is only responding to commands that request a JSON format response.

    QED!


  • administrators

    @cjm said in Aux Comms Issue:

    So, it looks as though via the Aux channel, the Maestro is only responding to commands that request a JSON format response.

    That's correct. Responses to other commands are saved until you ask for them using M408.


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