COTS servo controller for DC motor pair in opposing config


Thread Starter


Hi all!

I'm new to this industry so I'm in need of some help. I am trying to find a way to replace a very old (1990ish) custom servo controller with a commercial, off-the-shelf (COTS) servo controller. The motor configuration consists of 2 axis which both operate the same - 2 DC motors opposing each other. I think this is fairly common from what I've found in my research so far but I haven't found any units that specifically say they can control this type of setup.

I have chosen a ControlLogix PLC (company politics reasons). I have looked at Allen Bradley's controller, e.g. 1756-M02AE but it is not clear to me how it would be used for this config. By the way, the DC motors are controlled with an analog +/-10V command and encoder feedback.

Hi Kirk,

I have the same interest to use one of these modules 1756-M02AS or 1756-M02AE, for replace an old servo system, also the motor configuration consists of two DC motors connected in Anti-backlash, used in a Telescope, the servo used two close loop, one for velocity loop and the other for position loop, right now I’m just waiting information from the Rockwell Automation staff.

My idea is to use a controllogix PAC talking with the telescope system computer, The PAC has to control the velocity loop and read a precision encoder, and then, the system computer need to read the PAC encoder information every 20 hz, and then it has to calculated the position loop and pass this information to the PAC every 20 hz, the PAC is just a 'slave' of the Telescope computer.