Allen-Bradley CompactLogix Device Disconnects intermitantly

We have a Allen Bradley Compact Logix PLC connected via the built in OPC-UA driver and at least twice a day the connection is dropped and it does not reconnect. Selecting “Edit” under the Device Status page on the gateway, making no changes and clicking “Save Changes” is the only way I have found to get it to reconnect.

On the same gateway we have Siemens S7-400 devices connected a we do not have this issue.

We are on version: 7.6.1 (b2278) | 32-bit
Allen-Bradley driver suite for the OPC-UA module Version: 1.6.2 (b504)

This seemed to start after upgrading to 7.6.1. After the upgrade to 7.6.1 I tried updating the AB driver to the version above and that did not fix it.


Can you export the logs from the console page and then either attach the logs.bin.gz file here or email it into support?

Here is the file.

Hmm. The connection is definitely being closed by the PLC, not by Ignition. I’m not really sure why, however. It does look like it attempts to reconnect though.

You might try upgrading to the latest 7.6.3 release candidate, which contains a few fixes to the the CLX driver, among other things, that were ported from the 7.5.x branch after 7.6.1 was released.

You might also check out the status page for that CompactLogix device and see how many unconnected and CIP connections are used and how many are allowed.

So I’ve looked into the number of connections the device supports and we are well within the limits and it is on’y showing one connection from the gateway on the device.

I’ve updated to the latest version like you suggested and it still disconnected. So I tried taking the Concurrent requests down to 1 and so far that seems to work, but will that prevent data from updating properly if there are a large number of tags being read by Ignition?

Just to note, i updated to 7.6.2 (b2368)

Where do i get 7.6.3?

Yes, having concurrent requests set to 1 can start to limit you if the quantity of tags you’re subscribed to reaches the breaking point. You’ll know when that happens because you’ll start to get intermittent or permanent stale quality on your tags.

7.6.3 is still in the early access section - we’re still doing release candidates for it.

We are updated to the latest early release and the problem is not resolved.

You mentioned that it looks like in the previous logs that it is the PLC closing the connections. I don’t think that is actually the case. we didn’t see this issue before upgrading past the 7.5 versions.

We are working on adding a new project to the system for our Refrigeration system and it has a Control Logix PLC. I’ve added that as well as another CompactLogix PLC to the Devices. These are experiencing the same issues as well. This points back to something on the Ignition side of things.

I’ve included the latest log export for you to look at.

We are going to have our refrigeration system on Ignition shortly and we will need to get this resolved somehow, otherwise I’ll need to leave it on Wonderware and buy a development license for that. I really don’t want to do that.


You’ve clearly got some kind of regular network-level or OS-level interruption happening here. When your logix devices disconnect they don’t do it alone; your logs are full of intermittent periods where multiple devices at once (Cellar, Brewhall, HTCentrifuge, WWTP) experience timeouts and disconnects. It looks like this period lasts 2-3 minutes when it happens, and whenever what is causing the interruption finishes all comms go back to normal and there’s no errors or other messages in the logs related to the devices until the next interruption.

I’d start looking at the path between Ignition and the PLCs: OS, firewalls, faulty ports on a switch, ethernet cables run over by forklifts, etc…

I’m still troubleshooting this issue. I think it may be a network issue. I’ve disabled firewalls and it has helped, but it is still happening, less now, but still occurring.

This issue is solved. We found a bad network switch.