Stepper Motor Current

Hello everyone,

I am currently using 80MPD5.600S014-01 with X20SM1446-1.
From the manual, this motor is wired parallel internally which means it can run 6A.

I’ve done the following settings in the X20SM1446-1 configuration:

When measured in mappCockpit, I am only getting 3A for acceleration/deceleration phase, 2A for constant speed, and 1A for standstill. The graph from mappCockpit is shown below:

Would appreciate any inputs from the community. Thank you.

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On top of the issue above, when movement command is done, the stepper motor will move by itself very slowly to a position (Direction is normally opposite to the direction of movement) but on mappCockpit it is showing position = 0. Any idea why is this happening? Thanks.

I currently have not much time so only about first topic. The trace Datapoint is an Enumeration which shows only the selected Current (mode 0,1,2,3) , not a value in Ampere.

The only option to messure a Current is to use a Multimeter and connect it to the Motor wires.

For the Second Topic, please check if a Position Control is activ and if the Prediction Time ist set up. And if the Timing Settings are correct. We have here a nice Guide “Motion Commissioning for Beginners


I now had some more time to check your Configuration. Your Prediction and Total Delay time is Standard and you have the Position Controller active. A wrong Time Setting will result in false LagErrors and this will lead to a wrong behaviour of the Position Controller.

You can make a Trace of the Set,ActPosition and the LagError to analyse the Behaviour. But i think this could be your movement in Standstill, as the Position Controller is also active in this state and can issue a Movement.

Please check this Guidance for Setting the Prediction time. It depends on your Network Configuration.

I also would recommend to think about your Current-Settings, highest Values in Standstill looks strange, if Position Control is active i would at least recommend Standstill and Constand-Speed have the same Value. If needed the ChangeSpeed Value could be higher or Similar.


Hello Michael,

Thanks for the information provided.

I’ve now changed my current settings to as follows:

I’ve calculated my prediction time based on my network configuration:
0.004*8 = 0.032s
I’ve tried with 0.04s as well but my stepper motor is still giving move command in standstill as you mentioned in your previous reply. I’m playing around with the proportional gain value and so far I found that around 1 - 3.5 will make the lag error to oscillate around 0.

Below is the trace result I achieved by tracing lag error, set and actual position of the stepper:

Comparing my trace graph with yours from “Motion Commissioning for Beginners”, I’m not sure what is wrong with mine because I’m not getting the same shape as yours. Can you please advice further on this? Thank you.

I think your Trace looks now pretty normal and what to expect.
Some Additional hints:

  • You may consider to test 0.036 ms as well just to compare if it gets better or worse. The Formula showed for my tests some minor error for the -1 Modules. But you can only use Steps with a multiple of the Cycle time, so with high Cycletimes we might not hit the optimum.

  • With a 4 ms Cycle Time and a Bus-Cuppler + X2X Configuration which lead to this 32ms Delay, your Position Control can only be very weak. If you need a performant Controller you must optimize and invest Resources to get smaller delays.
    Try to get a direct X2X Bus at the PLC and reduce Cycletime , maybe with an additional Fieldbus Device just for the Steppermodules.

  • Think about your Stepper Encoder Resolution. If its a Standard B&R Motor with ABR Encoder it has 1024 Increments which is 0.35156° Degree. A Controller needs a higher Resolution to achive a better result.

  • Your Current Settings are now ok. As the Controller can move the motor in every PoweredOn State you now have enough current to move it. And in the event of Acceleration and Deceleration you have an additional little bit more. — Just a side hint, more current is not always better if you have small loads, high currents can have a higher Resonace behaviour. But currently your Trace does not show a Resonance for this Speed.

  • B&R is planing to release a new Stepper Module, which will have a build in Position Control to optimize Performance. You can ask your local Sales if you need details about it. High-Density Stepper Anouncement - Page 84

  • Just for a Test, try to make a messurement without Position Controller enabled to compare the results.

As far as i remember the Pictures of the Guide showed an application with 1.2 ms PLK+X2X = 9.6 ms , 16000 Inc Encoder Application.



One more question on my side, how do I know if my proportional gain is correct? Is it when my lag error is oscillating around 0?

See Chapter " Optimizing the control loop" of the Guide. There are some examples of different Proportional Gains.
Actualy it is the right one if the LagError is inside your required Limits and if its not a instable configuration.

For a better Description i hope you know a Teacher for PID-Control. I think he would have a more mathematical description.