Bad_failure on some tags across AB PLCs

Ignition
1

We are having an issue where some tags across multiple PLCs having a Bad_failure tag quality, and do not receive a value until we restart the OPC UA module on the gateway.

Normally, we saw this when live edits were being done on a PLC (seemed like edits to one PLC impacted polling to all) but that would resolve itself shortly after the edit finished. Now it seems to be happening when there aren't edits being done and lasting much longer requiring the module restart. There's no logs to indicate an issue, nor do we lose connection to the PLCs, there is also no communication overload (msg class 3 is fine as well), and all our driven tag groups are still polling like regular so I'm not sure where to look next.

I've read into some issues on the forum about online edits on Allen Bradley PLCs and also re-browsing, but I'm not certain thats what we are experiencing.

Gateway version: v8.1.27

We have multiple 5069-L340ER and L3100ERS2 PLCs on v33 firmware.

2

Eeewwww! That was plagued with bugs. You should flash update your PLCs.

That's pretty old, too. Lots of bugfixes since that was released.

3

Thanks Phil, controls team had talk of wanting to update to v36, I'll see if we can start testing that!

4

v36 has been pretty solid from what I've seen. Just have to be careful of the change to several instructions that changed like

  • MOV -> MOVE
  • LES, LEQ, GEQ, GRT -> LT, LE, GE, GT
  • Possibly more, but those are the most frequent ones I use

I'd say avoid v38 for now as it has a nasty bug that the Finalize All Edits button will sometimes just freeze Studio 5000 completely, and the only workaround last I checked was to do the old school 3 button method of Accept, Test, Assemble.