L_MC1P: The control deviation at the input of the position controller is unexpectedly limited to +/- half a motor revolution (corrected from V03.26.00)
Corrected from:
Library: L_MC1P_MotionControlBasic (FAST Motion) from V03.26.00
(Update via Package Manager)
Response of the new version:
The internal limitation of the control difference (tracking error) at the input of the position controller, which is effective by default, can now be deactivated if required.
Deactivation is done by setting bit0 in parameter subcode 009 of the motion axis.
What happens?
Position control in the PLC:
The control difference (tracking error) at the input of the position controller is limited internally to +/- half a motor revolution, which is not shown accordingly in the signal flow.
This limitation acts in addition to the output limitation (subcode 94).
If during operation the tracking error temporarily reaches larger values and the limitation becomes effective, this can have an effect on the achievable dynamics.
When does the behaviour occur?
Position control in the PLC (Axis_Ref subcode 90 = Position control ext. position encoder[1]).
The control deviation (tracking error) reaches values greater than +/- half a motor revolution.
Experience shows that the dynamically occurring control deviation is mostly at values significantly smaller than half a motor revolution, therefore the described internal limitation will not affect the drive behaviour in the vast majority of cases.
Only if larger tracking error values actually occur will the described limitation take effect and have a corresponding impact on the drive behaviour. However, in such a case it can be assumed that something is fundamentally wrong with the design of the drive system, the components used or the settings.
Possible causes for large tracking error values could be, for example, too strong filtering of the encoder signal or the encoder value is transmitted too slowly.
To remedy this, the filter time of the encoder axis (subcode 66) could be reduced.
