We have been experiencing "stuck" tag values in PCo. I reported the problem in this thread (http://scn.sap.com/thread/3345161) and was told to upgrade PCo 2.2 with the most recent patch. We did this, and the problem has become less frequent, but has not gone away.
In the rare cases when a tag value becomes "stuck" in PCo, this is what happens... the tag value changes; our OPC server accurately reflects this; but in PCo the value does not change. When this happens, we have been able to resolve this only by restarting the service for the PCO agent instance. What makes this worse is that if we restart the agent instance while machines are active, we tend to introduce more problems than we fix -- other machines get "stuck" values. Since our plant is open 24 hours a day, this is a major problem.
As stated above, upgrading to the latest patch of PCo 2.2 seemed to reduce the frequency of the problem, but did not make it go away. The last time this happened was the day before yesterday.
I checked the logs and got nothing for the past few days, so apparently no clues there.
As stated in my thread about cache modes (http://scn.sap.com/thread/3345160), I am tempted to to try setting Cache Mode to NONE, since this problem seems potentially caused by bad caching (a value may be cached and then not updated). Not sure if that is the ideal solution; it feels like that would be covering up a problem rather than fixing it.
I would appreciate any advice on resolving or troubleshooting this.
We have:
MII 12.2.4 Build(92) on a Linux server
which connects to
PCo 2.2 (2.203.1565.1805 Patch level 37637) on a Windows 2008 server
which connects to
FactoryTalk Gateway, an OPC DA server (OPC-DA 2.05a) running on the same Windows 2008 server
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