Upgrading to a motion control board

dangercraft wrote:

On the Minas drivers, and most of the other AC drivers I've come across, you can usually specify one of three types of control schema: position, torque and velocity. I'm not really quite sure what torque is useful for, but velocity control is what you are referring to where it wants +-10v DC. This is akin to using it as a spindle drive.
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In position control you use pulse and direction precisely the same way as you control a stepper motor.
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This way the amplifier continually updates the amount of power required to accelerate or decelerate according to the changes in input with the least amount of error and lag.

Ah, but this isn't the "LinuxCNC Way". The design principle of EMC (back before EMC2 even) was to move all the processing off of special-purpose hardware onto cheap generic computer hardware.
So, a typical LinuxCNC servo system uses the drives in velocity or torque mode and runs the position control loop in LinuxCNC. (one advantage of this is that you can see exactly what is going on (with Halscope) and change it)
LinuxCNC can comfortably run a 2kHz servo loop, and that is plenty fast enough, especially considering the raw horsepower of a desktop CPU.

I've googled for the NIST EMC docs before and found them... never tried to find the original code but I assume it is out there somewhere.

John