ControlLogix M02AE (Motion Module)

  • Thread starter B.P. Bompensiero
  • Start date

Thread Starter

B.P. Bompensiero

I am currently trying out this module for hydraulic servo control. I can not
get the channel I'm using for feedback recognize any of the counts. When I set the axis to "feedback only" I get a feedback fault. When I set it to servo, the fault goes away but I do not see any counts in the correct address locations
(or anywhere). Why do I get this feedback fault? Im using a 4x encoder, channels A and B with common tied to the A- and B-. Is there anything special I have to do in the software to read these raw counts? I have it scaled and tried
the GSV instruction as well. Can't currently get through to tech support!

Setbacken, Bob

It sounds like you have a unit with line driver outputs, and you are trying to use them in a way that is not exactly by the book. Try tying the A to the A- through a 1K resistor, and do the same with B and B-. Then take your output off one side of the resistor to your control.

Hope this helps,

Can you identify what feedback device you are using ?(Mfg, model/part no, etc.)
The M02AE has feedback loss detection circuitry which will kick in feedback only mode if A, or ~A, or B or ~B are "lost" or shorted to ground, which seems to be the way you are trying to
drive its inputs - it does want to see a differential signal, not single ended. There are some other things to consider when using this module to control a hydraulic system also. I'd recommend that you give the tech support team another try to help with your application. If you cannot get through with normal channels I will give you a contact number to try. If this hydraulic feedback device is really an SSI interface module there is an interface module option that may be necessary also.

Best regards,
M Fugere
Rockwell Automation
IMC Engineering Mgr/ Controls & Software


Is your feedback AqB with Z marker channel?
The M02 does not acknowledge feedback faults on a servo axis unitl the MSO command is issued.(for the reason of facilitating the drive enable hardware circuit, so you would not have to reset the fault each time you try to enable the axis)

You may call Allen Bradley Motion Technical Support at 603-443-5419 for assistance on this issue.