Help with M952/M953 increasing data rate



  • I am running a duet 3 with 4 expansion boards connected in the following order:
    Mainboard6HC --> Expansion3HC --> SAMMYC21 --> SAMMYC21 --> Toolboard1LC
    When performing synchronized moves (5+ motors) of small segments I noticed that movement of the toolboard stepper lags behind slightly. I need it to be fully synchronized with main board steppers. So I need to increase the data rate (thinking 2mb/s).
    My question is: Can I purely use the procedure of M952 outlined here:
    https://duet3d.dozuki.com/Wiki/Gcode#Section_M952_Set_CAN_FD_expansion_board_address_and_or_normal_data_rate
    setting mainboard last with M952 B0 S2000?
    and/or is it necessary/will help my cause to use M593 as well.
    If so I am a little confused on these two commands, does M593 affect the entire system or just the mainboard?
    Thanks,
    T


  • administrators

    You probably don't need to increase the data rate. There have been two relevant developments:

    • If you were using DAA then there was a bug that caused extruder movement to be delayed and sometimes steps to be lost. This was fixed in firmware 3.2.2.
    • At high step rates, various issues caused the synchronisation between main and expansion boards to be less than perfect. This has been addressed in firmware 3.3beta. There is an unofficial beta already available. I am currently preparing the official 3.3beta1 release.

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