I ran some tests tonight, rather it appears to be simpler than this.
Combining M400 onto the same line, delays the return of "ok", i.e.
G1 X100 Y100 F1000 M400
However, what if you want to receive the "ok" as confirmation of receipt, followed by "done". The following appears to do it, but if you don't send the M400 before the move finished, it doesn't work, which for very short moves is quite likely...
G1 X100 Y100 F1000
M400 M117 P4 S"Done" L0
In an attempt to resolve the issue in https://forum.duet3d.com/topic/35452/reading-general-purpose-inputs-in-duet-mini-5-returns-null, I upgraded the firmware on my new Duet Mini5+ from 3.0.something (not actually sure) to 3.4.6.
After a machine move, the steppers now make a loud continuous noise, but not continuous in the sense they're buzzing continuously, but the pitch and volume appears to randomly change.
I thought this must be because my configuration format was for an older firmware version, so I refreshed it using RRF config tool, but no change.
The axes still move and function correctly, but this is a significant difference in behaviour, so would really appreciate any input in getting to the bottom of it. Thanks!
EDIT - not sure how to post a response to my own question to show it as an answer... so just edited here instead. Issue resolved.
So, in config.g, in the M569 lines I've enabled stealthChop using the D3 flag, where previously the D3 flag was not provided. Presumably stealthChop was enabled by default in older firmware, and not in current firmware?
; Drives
M569 P0.0 D3 S1 ; physical drive 0.0 goes forwards
I posted this over on the OpenPnP Google group, which some of you may find interesting, if anybody else is trying to drive opto-isolated integrated steppers, and needs a suitable expansion board to do so.
@handyandy you can configure it directly, rather than tricking Duet into thinking it is a fan.
See my thread here, where I did exactly this to control some linear pull solenoids, and an LED ring light for a vision camera.
This way you'll be able to control your light using
M42 Pn S1 ; turn on your light
M42 Pn S0 ; turn off
Where n is the number you assigned to your light, via the M codes in my thread linked above.
In my case, both the ring light and solenoid required 24V so I used OUT5 and OUT6, with the voltage select jumper set to VFUSED, as I too am supplying the board with 24V.
Alternatively you can configure the jumper to supply 12V on these pins, if you're within current limits.
Finally, I'd need to check the schematic to see if the outputs are just low side MOSFETS, in which case you likely can externally supply whatever voltage you need (within the drain-source breakdown limit of the FETs) and just use the ground side of the output pins, but take this last paragraph with a pinch of salt, as I've not done that check.