Eliminated from:
8400 HighLine and TopLine: FW version = 13.00.00.00
Response of the new version?
When the limit switch monitoring responds repeatedly after a reset, the error response set is also executed again.
Which products are affected?
8400 HighLine and TopLine: FW version ≤ 13.00.00.00
What is the response?
In spite of the fact that the limit switch is approached, in the 'Position follower' operating mode the drive synchronises to a master position outside the limit switch ('lock to electrical shaft'). Then, however, the slave drive does not follow the master position, which causes a deviation between the master and slave drive positions ('Position follower' operating mode does not follow the master value).
When does the problem occur?
The response occurs after
- the drive has approached a limit switch in the 'Position follower' operating mode for the first time, and
- the limit switch error has been acknowledged by the user, and
- the limit switch has not been exited via the 'Retract limit switch' function (subfunction in the 'Manual jog' operating mode), and
- the same limit switch is approached again in the 'Position follower' operating mode, or has not been retracted yet.
Diagnostics options?
The response may potentially occur if bit 10 (positive hardware limit detected) or 11 (negative hardware limit detected) of the C1241 status display remains set although a limit switch error has already been acknowledged.
Short-term measures/recommendations?
If a limit switch is triggered, retract the limit switch via the 'Manual jog' operating mode, i.e. either using …
· the 'Positive manual jog' traversing command if the negative limit switch is busy (control bit 4 in MCK control word 1)
· the 'Negative manual jog' traversing command if the positive limit switch is busy (control bit 5 in MCK control word 1)
· the 'Retract limit switch' traversing command; this command works no matter which of the limit switches is busy (control bit 7 in MCK control word 1)
Like this, bit 10 or 11 in the MCK status display C1241 is reset, and repeatedly approaching the limit switches in the 'Position follower' operating mode causes another error message and disconnection of the drive.
Evaluation:
In the 'Position follower' operating mode, the response causes critical operating states since the limit position monitoring via hardware switches does not work as expected. The first approach of a limit switch trips an error message, but after the error has been acknowledged, every further activation of the limit switch does not cause an error message anymore. Machines with a limited traversing range are therefore endangered without further, external means of monitoring.
As a consequence of the limit switch error and its assumed acknowledgement, however, the 'Position follower' operating mode is no longer reliably executed although this is displayed in status code C1243/0: When the 'Position follower' operating mode has been selected again, the slave drive executes positioning to the master position, but it does not follow this position after the synchronisation has been completed. In the case of mechanically coupled drives, this response may cause damage to the machine (e.g. distortion of gantry mechanics).
