OPCUA Server Quick Client Reads but cant subscribe

Please help. I have multiple micrologix 1400 devices that are subscribed to just fine, but I have one micrologix 1400 that the boolean values (and only the boolean values) can be read from the device in the quick client, and they read fine but they cannot be subscribed to (returns bad, unspecified). I’ve restarted the OPC module, deleted and reconnected the micrologix 1400, made sure that the binary values are global,… I’m at a loss. Any suggestions?

This is an obvious use of fault finding question powers! :grinning:

  1. Did this problem just start, or has it always happened?

  2. If it just started, then what changed?

  3. What is the same about the systems that work?

  4. What is different about the system that doesn’t work?

But that’s about my limit. I touched a micrologix once several years ago, but that’s all I know about them.

Just started from what I can tell. Nothing changed. The systems that work have the same exact settings. the only difference about this micrologix is the device itself.

Does the magic power cycle work?

First thing I did.

Anything funny in the Ignition log files?

nothing that I’ve been able to identify.

Unfortunately you’ve exhausted my skillset. Sorry I can’t help.

Pretty much every time I’ve seen this the cause has been a tag somewhere addressing an address that is out of range or no longer exists in the PLC.

When you try to subscribe the tags are getting put into the same request as this bad tag and it’s making the whole request fail. When you read in the QC it’s not combined with the bad subscribed item and it succeeds.

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An approach to finding the problem tag is to disable half of them. If the problem goes away, its in the group you disabled. Turn half of those back on to see if the problem returns. et cetera. (If the problem doesn’t go away/doesn’t return at any step, switch which half is disabled. Work from a tag export where you’ve searched for the device name to make sure you don’t overlook any.

Sounds like a binary search :slight_smile:

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What addressing do you use as B3:35/3 always work for me so far, but B3:35.3 sometimes work

Well, got on the horn with ignition support, no luck, nothing showing up in the logs either. They had never seen it… so… I created a second Binary group on my 1400, and that solved it. Maybe a driver issue. Who knows.