Originally Posted by
Jim Dawson
I have not had this problem with either servo or stepper driven machines with linear scales. Requires proper tuning of the servo loop. I have not run my servos as dual loop, just tie the motor encoder to the drive as normal, but read and control the position from the linear scales.
All of the Galil motion controllers made in the last 20 or more years will support dual loop. The later generations also have stepper dual loop control capability built in to the firmware to save programming time using the S-n command set.
All of the Galil 2xxx and 40x0 series controllers offer serial and ethernet communications, the 22x0, and 40x0 series also offers USB communications. There are Galil plugins available for Mach3/4. All of the Galil controllers are Step & Dir compatible.
Yup, expensive compared to the hobby class devices, these are real industrial class motion controllers, I use them exclusively on my machines. There are normally good deals on the used market from EBay vendors, but know what you are buying. For highest performance use the 18x6 or 40x0 controllers. Part #'s 18x0, 18x6, 20x0, 22x0, 40x0 (where x= # of axes) are fine. Other part numbers may work, but not recommended.