We have a 315-2 PN/DP v2.6 CPU, where a MES system (coolplex) is communicating with via the Simatic net OPC server (v6.4) through the ethernet interface. OPC server is running on Windows server 2003 R2.
The MES system is reading/writing to a DB of 56 bytes, where a command made of 12 bytes is written to the PLC.
For the last 2 years, it worked fine, but since a few weeks, now and then, some values of the command are no longer written to the CPU, although the writing of the command hasn't changed.
It happens up to 20 times a day that suddenly 1 or 2 values are not written. When the MES system rewrites the command, everything comes through again...
Anybody any idea what may cause this or how i can log the OPC server what is happening?