For the PID settings for a hardware stepgen, P should normally be
1/Servo-thread-period so 1000 for a 1 ms servo thread period,
and FF1 should be 1.000.
The physical meaning of these setting is this:
P=1/Servo-thread-period means correct any detected position
error by the next servo thread invocation.
FF1= 1.000 means set the base stepgen velocity to LinuxCNCs commanded
velocity (to center the operating point of the PID loop on the current velocity)
This means the P term has little to do besides correcting for minor time base
differences between LinuxCNC and the hardware.
