Hello. I have a machine with 2 independent Z motors which contains X and U axis respectively. The Z motors drivers are mapped together Z0.2:0.5 for both Z motors to move in sync. While they are in sync, is it possible to set separate steps per mm for each Z motor like below with Z1000.00:1020.00 ? (I tried below configuration but there is no Z movement response) So that driver 0.2 uses 1000 steps per mm and driver 0.5 uses 1020 steps per mm.

I'd be very grateful for any recommendation on how to do so in config.g. Thank you very much.

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 Z1000.00:1020.00 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

@droftarts thank you for your advice.

I now understand that a K value can be inserted to M558 command to configure separate z probes.
what about M950 where the BLtouch servo pin is declared, how do I change M950 command for each servo to correspond to each k value Bltouch specifically?

Thank you very much.

Hello, I'm currently building a machine which has 2 independent Z towers (1 for each extruder, similar to Zidex https://www.drdflo.com/pages/Projects/Zidex.html). The 2 towers are synced during operation, but separately operated during z homing.

In homez.g, I have configured the BL touch declaration separately, and only when the BL touch is needed for homing each tower.

The movements are executed per expected, BL touch for Tower 1 and Tower 2 are declared and G30 bed probe accordingly. However, I adjust the Tower 2 Z trigger height of Bltouch, the offset is applied to the first BLtouch of Tower 1 together with Tower 2, which is unexpected.

Therefore, I'm unable to make Tower 1 nozzle and Tower 2 nozzle to lightly touch bed at z=0, when Tower 1 nozzle is perfect, Tower 2 nozzle is too far from bed, when Tower 2 nozzle is perfect, Tower 1 nozzle reaches too low into bed.

I'd like to seek any advice to see why my configurations of homez.g having separate BL touch configurations, the Z trigger height seems to apply to both cases.

I'd be grateful for any help and happy to supplement with more details. Thank you very much in advance.

; homez.g
; called to home the Z axis
;

M584 Z0.2                                   ; Split the 2 Z towers for independent control. this will move tower 1 only
T0 P0                                       ; Select Tool 0 without running tfree tpre tpost

G1 X0 Y0 F6000                              ; 
G1 X150 Y150 F6000                          ; move T0 into center position

M950 S0 C"io7.out"                          ; create servo pin 0 for BLTouch 0
M558 P9 C"io7.in" H10 F300 T6000            ; set Z probe type to bltouch and the dive height + speeds
G31 P500 X-45 Y-75 Z2.5                       ; set Z probe trigger value, offset and trigger height
M557 X30:280 Y30:280 S50                    ; define mesh grid

G30                                         ; this will home and probe the tower 1
M280 P0 S160                                ; retract again if probe retract fails
G29 S1 			                            ; load height map

M584 Z0.5                                   ; Split the 2 Z towers for independent control. this will move tower 2 only
T1 P0                                       ; Select Tool 1 without running tfree tpre tpost

G1 U150 Y150 F6000                          ; move t1 into center position

M950 S0 C"io4.out"                          ; create servo pin 0 for BLTouch 0
M558 P9 C"io4.in" H10 F300 T6000            ; set Z probe type to bltouch and the dive height + speeds
G31 P500 U35 Y10 Z2.5                       ; set Z probe trigger value, offset and trigger height
M557 U50:250 Y50:250 S50                    ; define mesh grid

G30                                         ; this will home and probe the tower 2
M280 P0 S160                                ; retract again if probe retract fails
G29 S1                                      ; load height map



T0 P0                                       ; Select Tool 0 without running tfree tpre tpost
M584 Z0.2:0.5

;DEFINE IO7 PROBE AS DEFAULT
M950 S0 C"io7.out"                          ; create servo pin 0 for BLTouch 0
M558 P9 C"io7.in" H10 F300 T6000            ; set Z probe type to bltouch and the dive height + speeds
G31 P500 X-45 Y-75 Z2.5                     ; set Z probe trigger value, offset and trigger height
M557 X30:280 Y30:280 S50                    ; define mesh grid

@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!!

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

@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

@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

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