Which products are affected?
ECS axis module B-SW V6.7
EVS93xxEI (Servo PLC V6.5)
EVS93xxET (Servo PLC V6.5 equipped with technology function)
What happens?
If the value for the DC-bus voltage falls below the permissible limit, the drive generates an LU message which may lead to a task overrun in a time-controlled task (interval task). The PLC target system is stopped.
When does the problem occur?
Among other things, the error memory is saved in a mode protecting against mains failure when the value for the DC-bus voltage falls below the permissible value. Dependent on the run-time of the cyclic task and the utilisation of the time-controlled task this saving process may lead to a task overrun in a time-controlled task.
Possible diagnostics?
Check the utilisation of every task in the Task monitor (DDS tab 'Resources').
If a task overrun has occurred, code C0161 indicates a value between 201 and 208, dependent on the task informing about the task overrun.
Short-term measures/recommendations?
Reduce the program logic in the cyclic task (PLC_PRG and its subprograms) to a minimum. Set the time slice interval (C2100) to 26 ms and the changeover between the time slices to the end of the cyclic task and system task (C2102 = 2). Use the Task monitor to check the utilisation of the time-controlled tasks. This function restriction does not appear if
Task interval time > (run-time of the time-controlled task) + (run-time of the cyclic task) + 70 µs
Evaluation:
If the value for the DC-bus voltage falls below the permissible limit, a task overrun may occur. Since the saving process described is very short it is very improbable that a task overrun occurs.
