Corrected from:
- Library: L_MC1P_MotionControlBasic (FAST Motion) V03.12.00.70
(contained in PLC Designer V03.12.00.177 and higher)
Response of the new version:
The homing state behaviour has been corrected.
When switching off and on only the drive controllers via the 24-V supply without restarting the control system as well, the homing state will now be reset (IsHomed=FALSE).
This ensures that homing must be repeated.
After switching off and on only the drive controllers via the 24-V supply without restarting the control system as well, the homing state erroneously indicates okay (IsHomed=TRUE).
In general, the measuring system's reference to the mechanics (reference) gets lost during this process. If a positioning process is started in this state, unexpected movements may occur, in some cases, until the response of the travel range monitoring function (limit switch) as a result of which the drives will be stopped.
When does this behaviour occur?
The behaviour occurs if position reconstruction is deactivated (default setting) so that homing is required after every mains reconnection.
While the control system is operated continuously, without reinitialisation,
only the drive controllers are switched off and on again via the 24-V supply
and the EtherCAT bus is restarted.
Which products are affected?
- Library: L_MC1P_MotionControlBasic (FAST Motion)
(contained in the PLC Designer)
Short-term measures:
- If operation has been interrupted as described above, repeat homing for the plant/machine under normal operating conditions irrespective of the indicated homing state.
- As an alternative, position reconstruction can be activated to avoid the described behaviour.
For this, the application must meet the following requirements:
When the 24-V supply is switched off, the rotation of the motor shaft must not exceed the absolute display range of the feedback system.
Resolver (1 pole pair, 2-pole): +/- half a resolver revolution
SinCos absolute value encoder: +/- half the absolute display range of the encoder (with 2048 rev. practically hardly attainable) - The Logical Read Write (LRW) function of the EtherCAT master must be deactivated (default setting is active)
Evaluation/recommendations:
Due to the above-mentioned conditions of occurrence, this case will occur only rarely.
Usually, control cabinets/systems are switched off and on centrally and completely. In this case, the homing state will always be reset correctly so that homing will always be required after reconnecting the mains.
