ABMicroLogixTransport : Error getting value from bytes=null

Ignition
1

I am getting random errors in my wrapper.log files that I can’t figure out. Is this a problem that anybody knows about?

INFO   | jvm 1    | 2019/09/25 15:39:02 | W [c.i.x.d.a.t.ABMicroLogixTransport] [22:39:02]: Error getting value from bytes=[0, 0, 0, 0]
INFO   | jvm 1    | 2019/09/25 15:39:02 | W [c.i.x.d.a.t.ABMicroLogixTransport] [22:39:02]: Error getting value from bytes=null
2

What version of Ignition is this?

3

Version 7.9.10, Running under Ubuntu 14.04 – And Oracle Java 8

4

Same thing started happening to us a couple of days ago. This has never been an issue for years that its been running. Same version of Ignition running under Windows Server 2012 R2. The affected PLC was using the A-B Logix Driver. To solve this temporarily, I just simply dragged a PLC tag from the OPC Browser onto our tag list and a few seconds later all offending tags started getting fixed (as in the red quality overlay disappeared) from that PLC. A few days later it happened again. So this is not a real fix. One thing to also note is that another/different PLC using the A-B MicroLogix driver was disconnected to do some maintenance…and the device in Ignition was left as Enabled so it always showed bad quality and was generating the same identical errors in the Log file. Once I disabled that PLC, errors in the logs went away. Now I’m waiting to see if this somehow affects the first PLC tags.

Also, the Automatic Rebrowse option is not enabled on all PLCs. image
So, this may explain why adding a new tag causes the system to begin re-polling those tags. I still don’t know why it would stop polling though.

5

Does anyone have an explanation for this problem ?
I'm having it with one of our customers.

The device remains in the "Connected: Protocol: Bridged_EIP" state and its associated opc tags are in the "Bad_Failure" state.
No trace of error in the device's Log Activity.

Right-click Restarting Tag to unlock tags. The quality changes to Good and the value appears.
But this manipulation is not acceptable in production.

6

I stopped the software and started it again.
I think it fixed the problem