I was finally able to try out your suggestion this weekend and of course stepgen produces exactly the number of pulses it's supposed to.
So I also connected the motor encoder to the 7i96s and used it to calibrate the number of steps/mm and it turned out to be 456, which is exactly 5% fewer than expected. Since my small pulley has 20 teeth, this led me to inspect the mechanics again and it turns out I have T5 pulleys with an AT5 belt, which resulted in it skipping one tooth forward once per motor rotation. Then I guess occasionally it wouldn't skip and my machine would lose it's position.
Thanks for your help, I learned a lot more about hal. I just have one more sort of related question: can you tell me the capacitance and voltage of the C73 capacitor on a 7i96?
