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Intermittent issue with RSLinx - OPC Interface and no data

Question asked by ChipStacy on Oct 1, 2018
Latest reply on Oct 9, 2018 by ChipStacy

We have well over 100 Rockwell PLC's of varying models SLC500, Control Logix, Compact Logix etc. Often our portable systems are powered down and disconnected from our PLC network. When reconnected we often experience issues with no PI data showing up on Processbook. We get the dreaded 'Trace'. The PLC's have no issue when connecting to our PLC network and are easily seen via programming software and RSLinx.


There are several scenarios that occur with regards to getting data back into PI. As a starting reference we have two PI servers, a primary and backup. Both servers run RSLinx and PI's OPC interface version and UniInt (universal interface)

First scenario with no PI data:

     PLC is connected to network but cannot connect to or see any data with PI OPC Client. Solution is to shutdown opc interface. Open RSLinx, delete the topic for the affected plc, rebuild the topic, restart the interface and then we're back in business.


Second scenario is that we can see PLC data in OPC client on both servers but still get 'Trace' with Processbook. In this case, we restart the opc interface on the backup server, wait for it to be started, then stop the interface on the primary server, which in turn forces the backup to become the primary, then restart the old primary (now the backup server) and then Processbook data starts showing data points from the PLC.


This is a regular issue with anything that's been disconnected from the network for any length of time. Sometimes it comes back and many times it doesn't.

We use the same OPC interface for another portable system by GE that doesn't use a PLC but rather a PC and we've never had an issue. ONLY with Rockwell PLC's.


We've yet to determine what is causing this. We believe this to be an RSLinx issue but have had no luck with Rockwell as of yet in resolving the issue.


Thanks for your comments in advance.