Eliminated from:
9400 HighLine SW V7.0
Behaviour of the new version?
The erroneous inclusion of the phase position set in C1122 when calculating the C1123 time slot has been remedied. The time slot for monitoring the synchronisation signal now only corresponds to the sync tolerance set in C1123.
Example:
Sync phase position C01122 = 400 µs
Sync tolerance C01123 = 20 µs
=> The effective time slot for the monitoring function is 20 µs long!
Description of the problem
The system variable SYNC_bSyncInsideWindow of system block LS_SyncInput shows the status TRUE, although the control program of the axis to be synchronised does not receive the SYNC telegram on the CAN bus within the tolerance window defined in C1123.
When transmitting electrical shafts via the CAN bus, the incorrect status information in SYNC_bSyncInsideWindow may lead to temporary fluctuations in the setpoint and, consequently, to audible drive noise if the electrical shaft is activated too quickly after the control voltage has been connected.
When does the problem occur?
The problem occurs if the control program cycle of the controller is to be based on a SYNC telegram on the CAN bus and the phase position of the SYNC telegram in C1122 is set to a value greater than zero. The tolerance window for generating the status signal SYNC_bSyncInsideWindow is erroneously calculated as the sum of the phase position in C1122 and the actual tolerance window in C1123.
Example:
Sync phase position C01122 = 400 µs
Sync tolerance C01123 = 20 µs
=> The effective time slot for the monitoring function is 420 µs long!
Which products are affected?
9400 HighLine SW ≤ V5.1
Diagnostics options?
The behaviour can be diagnosed by using a hardware oscilloscope to record a digital output, which is toggled on a cyclical basis, on the master drive (drive that sends the SYNC telegram on the CAN bus) and on the slave drive (drive that synchronises with the SYNC signal from the CAN bus). The temporal positions of the digital output switching edges can be used to work out the starting time of the control program cycle of the following axis and, thus, the setpoint status of system signal SYNC_bSyncInsideWindow. However, the actual status of SYNC_bSyncInsideWindow is set to TRUE much sooner than this.
Short-term measures/recommendations?
None.
Evaluation:
If the status signal SYNC_bSyncInsideWindow is used in existing systems, this error elimination measure shortens the monitoring window by the same amount as the phase position, if phase position C1123 is set to a non-zero value. Under certain circumstances this may result in monitoring of the synchronisation signal (as programmed by the user) being triggered in error. Increasing sync tolerance C1123 by the same amount as the phase position originally set in C1122 will rectify this.
Published with Service Message No. 38/2009
