we've got a DM542T Driver running as external Driver on the Duet Wifi 2.
The Problem is that the steps/mm from the Duet is not working properly.
The Driver is set up to 6400 Steps/rev. On the Z-Axis is a TR3 Screw.
This would mean 6400/3mm is 2133.3 steps/mm.
We tried this Setting and the travelled way is About Faktor 10 to small.
This means to get it working properly we Need to Setup the steps/mm to arround 21000.0 . This high value of needed steps means only very low reachable speeds.
We already tried different Settings on the Driver and there is Always arround factor 10 to small.
What movement speeds are you trying to use when you move the Z axis? Your M203 Z movement speed limit is set to 12000 (200mm/sec). This is almost certainly much faster than your Z axis can do, and it would also require an unfeasibly high step rate. Try using a much lower value such as 300.
We started with a Z-Speed limit of 50mm/s or 3000mm/min. This should not be a problem of feasibility with appropiate accelaration settings. There was exactly the same issue. We changed it to exclude a problem here.
I think it is more a problem of voltage level or step/pulse timing.
Unfortunately I have no oscilloscope to check the quality of the step/dir signal of the duet wifi 2.
Are you using the expansion breakout board, or =have you connected the external stepper driver inputs directly yo the expansion header?
@robinfaurecia Check the voltage levels on the output.
Most external drivers (including the DM542T) require at least a 5v step/dir signal, while the duet will put out 3.3v by default. This works on some 5v systems but is not guaranteed and can lead to inconsistent behavior.
If you're not already using it, this product breaks out the expansion motor signals to 5v differential outputs which can help with external driver compatibility.
Beyond working on the signal itself, could you reduce the microstepping to the motor? At x32 microstepping with a 3mm lead screw that is a Z resolution of 0.0005 mm which may be finer than needed for your application.
Reducing it even to x8 would still leave you with a Z resolution of ~0.002mm and cut the steps by a factor of 4.
Of course this depends on what you actually need out of the Z.