Duet3 Expansion 3HC Motor Current Issue

demodemo

Hello, I'm new to Duet boards and now using a Duet3-6HC with Duet3-3HC. My XYZE axis powered by 6HC is working normally on 24V producing good 3D prints.

I'm now experimenting to use 3HC expansion board to drive a new U axis with a U-endstop. I've hooked up the board to 24V PSU and via modem cable to 6HC.

M119 shows that the endstop on the 3HC is working.
But when I do M17 to activate U motor as a test, the motor is activated but only provides a tiny fraction of holding torque which is irregular.

I'm unable to proceed with moving U motor until I can find out what reason causes such weak holding torque, I've set the motor current of U motor the same way as XYZ motor as shown in config.g.

Actions I've tried yet producing same result:
Swapping Cables
Swapping Driver Slots (with config.g adjusted) on 3HC
Swapping Motors

Thank you very much to the community in advance if any help can be offered. Thank you.

; Drives
M569 P0.0 S1                                    ; physical drive 0.0 goes forwards
M569 P0.1 S0                                    ; physical drive 0.1 goes forwards
M569 P0.2 S0                                    ; physical drive 0.2 goes forwards
M569 P0.3 S0                                    ; physical drive 0.3 goes forwards
M569 P0.4 S0                                    ; physical drive 0.4 goes forwards
M569 P0.5 S0                                    ; physical drive 0.5 goes forwards
M569 P1.1 S0                                    ; physical drive 0.6 goes forwards

;M584 X0.0 Y0.1 Z0.2 E0.3:0.4                   ; set drive mapping
M584 X0.0 Y0.1 U1.1 Z0.2:0.5 E0.3:0.4           ; Xu, Zu, set drive mapping

M350 X32 U32 Y32 Z32 E32:32 I1                  ; configure microstepping with interpolation
M92 X160.00 U160.00 Y160.00 Z1000.00 E840.00:840.00      ; set steps per mm
M566 X900.00 U900.00 Y900.00 Z60.00 E120.00:120.00       ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 U6000.00 Y6000.00 Z180.00 E1200.00:1200.00 ; set maximum speeds (mm/min)
M201 X500.00 U500.00 Y500.00 Z20.00 E250.00:250.00       ; set accelerations (mm/s^2)
M906 X1000 U1000 Y1000 Z1000 E1000:1000 I30     ; set motor currents (mA) and motor idle factor in per cent
M84 S30                                         ; Set idle timeout

; Axis Limits
M208 X0 U0 Y0 Z0 S1                             ; set axis minima
M208 X310 U310 Y400 Z300 S0                     ; set axis maxima

; Endstops
M574 X1 S1 P"!io1.in"                           ; configure switch-type (e.g. microswitch) endstop for low end on X via pin !io1.in
M574 Y1 S1 P"!io2.in"                           ; configure switch-type (e.g. microswitch) endstop for low end on Y via pin !io2.in
M574 U2 S1 P"!1.io1.in"                         ; configure switch-type (e.g. microswitch) endstop for high end on U via pin !1.io1.in
M574 Z1 S2                                      ; configure Z-probe endstop for low end on Z

deckingman

@demodemo The usual cause of poor torque is that the motor isn't wired up correctly. Have you identified the motor phases for the particular motor you are trying to use? A quick check you could do is try one of your other motors that you know works correctly.

demodemo

@deckingman Thanks for the reply. I've used different motors, different wires, different slots on 3HC to test, yet the behaviour remains the same. The same U motor when powered as X axis from 6HC works fine. So I wonder if it has something to do with 3HC wirings or my config.g that produces this strange result.

ps: my motor is Nema17 and that's the only motor my machine uses

deckingman

@demodemo I don't see anything obvious in your config.g. I'm running 3 expansion boards, one of which has 2 Nema 17s running at 1800 mA and 1 Nema 23 running at 2300 mA. So the board is more than capable of running of running 1000mA. If you've tried all 3 drivers on the board, and they all exhibit the same behaviour, it's highly unlikely that all 3 drivers have failed. And as you' have tried other motors which are known to work, then the only thing I can think of which would affect all 3 drivers, is the voltage supply to the board. Have you checked that? Is it the same voltage as your 6HC? Does the voltage drop if you command motor movement?

demodemo

@deckingman
The 3HC draws power from the same PSU as 6HC, and I don't see any voltage drop as I activate motor on 3HC. On 6 HC, an enabled stepper circuit measures 1.3V, while on 3HC my enabled stepper reads only 0.2-0.3V. Another possible clue is when I turn on the board, I receive several error messages related to Board 1, do you think possible software errors result in insufficient voltage/current fed to the drivers? Thanks for the help

T3P3Tony

@demodemo you should not be getting those messages on start-up: that indicates there something is not right in the communications between the 6HC and the 3HC.

What firmware version are you running on the mainboard and the 3HC (send M115 M115 B1)

Do you have G4 S2 at the start of your config.g to let the expansion board startup before mainboard tries to configure it?

deckingman

@demodemo As Tony said, you should not be getting those error messages and yes, this could well be the problem. The drivers are fed with step pulses as well as enable and direction signals. So if your expansion board isn't communicating properly with the main board, then all sorts of havoc will ensue.

demodemo

@deckingman @T3P3Tony thank you for the prompt reply. I'll try to resolve the software issue first and report back my findings.

demodemo

@deckingman @T3P3Tony Thank you very much for your advices. I've done a M997 B1 firmware update on my 3HC and now the stepper torque is back to normal and I can continue my U axis construction. Thanks!!