Which products are affected?
9300 servo cam
What happens?
There are drifts at the drive, possibly to both directions of rotation.
When does the problem occur?
The drifts at the y-axis of the cam can occur in applications with synchronised stretching and compression. Due to a base configuration (e. g. C0005 = 10000) the functionality for a stretching and compression of the curves synchronous in curve pulse is available in the configuration. The function ensures that an asynchronous switchover of the evaluation factors at the curve's y-axis (YSET1-FACT) does not lead to calculation errors.
This function is applied to the speed setpoint of the y-axis in the field of ± 15000 rpm.
Values > 15000 rpm and stretching / compression of the y-axis leads to drifts. In order to avoid the problem it has to be ensured that at the y-axis of the curve during operation there are no position jumps. The behaviour often occurs when following boundary conditions of the application are fulfilled:
- The function touch probe correction at the x-axis is applied.
- In the process the x-axis of the curve is reset or set to a start value (CDATA-XRESET).
- An offset is tightened to the x-axis.
- In the application motion profiles are chained whose boundary values do not match with the position and speed (position jumps, speed jumps in the transition).
Possible diagnostics?
The implementation of one integrator each (FB PHINT) in front of and behind the function block YSET1 permits the evaluation of the position before and after stretching / compression and consequently conclusions regarding the occurring drifts.
Short-term measures/recommendations?
There are following possibilities to avoid the drifts:
- Apply label synchronisation of the x-axis (x-touch probe) only in 'TP speed mode' 'with compensation limitation' and limit the catch-up speed (C1335 = 1, parameterize C1331)
- Do not execute the phase shift of the master axis (x offset) abruptly, but round (e. g. via FB RFGPH2)
Possibly an x-offset can be processed internally by means of the TP function. More information about the functions x-offset and x-touch probe can be taken from the 9300 servo cam documentation.
Evaluation:
Until now in all affected applications the problem was caused by misapprehensions in the configuration or by cam profile data generation. The function protection will be integrated in future releases.
