Fatal Following Errors on Motion Program Abort

[abeard]

Hi,

We are experiencing Fatal Following Errors on single motor motion program aborts. We use a 32kHz external time base while the motion program is running. We then periodically issue aborts to prematurely terminate the motion program. In a separate PLC, we monitor the coordinate system and if the motion program is done we subsequently reset the time base to the local crystal. I suspect that some misunderstood interaction between the PLC resetting the time base and the controlled stop abort is what is triggering the fatal following error.

 

I’ve tried monitoring desVelZero in the PLC to wait until the motor is (mostly) stopped before resetting the time base, but this did not seem to help the problem.

 

Any advice here would be very much appreciated.

 

Thank You.

~Andy

[Alex Anikstein]

Andy,

 

Are you sure that your Motor[x].AbortTa and Motor[x].AbortTs are set to reasonable values for your system? Those parameters are only really used when issuing an abort to control the deceleration profile, so if they were set wrong, you likely would not notice it otherwise.

[steve.milici]

Also note that it could be possible that the motor may still be in motion when you “reset the time base”. If the time base slew rate (Coord[x].TimeBaseSlew) is at a high value this could result in a “jump” on the motor, however small, but enough to cause a fatal FE. Reduce this at the "resetting point" to see if it helps.

[abeard]

Thanks - we were using the default AbortTa and AbortTs. Shoring these up seems to have fixed the issue. Thank you.