Duet v0.8.5 - Problems with adjusting the motor current using M906 (1 reply)

Hi everyone,

I am using the Duet v0.8.5 with RepRap Firmware (dc42 fork: 1.09k) for controlling a delta printer.

The gcode command M906 is used to adjust the motor current. Unfortunately the chosen motor current differs a lot from the true motor current.


Example:

M906 X1600 Y1600 Z1600 E300 I60

X,Y,Z-Motors should run with 1600mA (4800mA in total) at 12V right?

If I meassure the actual current supplied there are only 1680mA in total. Minus 130mA for the board = 1550mA. This means around 500mA per motor.


I guess it doesn't work correctly because the coil resistance of my stepper motors is different to the resistance of the motors normally used. (I have 1,65 Ohms per coil)

Any other ideas?
What do I have to change in the firmware to get the correct current?


cheers!