Communication problems between the CPU and FM-NC with operator control device
When using the more recent S7-CPUs, problems can be encountered for the communications to the operator control device of the FM-NC.
With the new CPUs (e.g. CPU315-2DP, 6ES7 315-2AFx3-0AB0), problems can occur, e.g. when displaying the status of the PLC using the operator device.
This problem can be caused by a setting in the CPU which can be easily changed.
More detailed information on the CPUs involved and to resolve the problem can be taken from the FAQ ID: 12604880 "No cyclic read task possible for CPU 314/315 – error message 33:55301(D805)".