7i76 in spindle velocity mode

Festive days to all

I'm running mill with 5i25 + 7i76

net connect-power 24V to DAC => magic smoke #

Now i'm trying to save the card by configuring stepgen3 as spindle control.
Have Xinje servo motor control and spindle - it can accept 0-10V (and PWM control i believe)

On the HAL scope i noticed results on stepgen.3.step ( PWM?), but have failed to get any reaction on the cards output
Have tried hm2_5i25.0.stepgen.03.step and hm2_5i25.0.7i76.0.0.stepgen.03.step with all sorts of variation, but no result.
( measured with volt meter and checked with hal-scope).

Question: how do i get the signal out ? rgds Wilfried

You can get PDM (Pulse Density Modulation) out of a stepgen by setting it into velocity mode.
This means you will get a constant pulse length but variable frequency. For example if you set stepgen 3 into velocity mode, link the stepgens velocity command to the spindle speed and set the steplength to 100 usec (100000 ns), step space to 100 ns, you will get PDM modulation on the step pin with a spindle speed range of 0 to 10000 generating a PDM of 0 to 100%

Its probable better to use real PWM however, to do this you would need to use firmware that replaces one or more of the 5I25s step generators with PWM channels