Tag is Bad Quality in UDT

I have been using a UDT for a template I am working on. One of the Bools inside of the UDT is showing bad quality but I can’t seem to figure out why. I have tried deleting the tag and recreating it. That did not work. I then tried to delete the tag out of the UDT and recreate the tag inside the UDT and that did not work. I then created a OPC tag pointing directly to the Bool value in the PLC and that also did not work. Any ideas would be helpful. The other 6 Bools inside of the UDT work just fine.

What’s the plc? If AB, is the tag set to read/write in the plc?

The PLC is AB and the bool was set to None inside the Addon Instruction. My engineer just gave me a host of these instructions. Think I will take a bit closer look at the rest of them Thanks nminchin.

Before you get too far into things, know it’s better to use UDTs vs AOIs. I tried to be stubborn, but in the end had to spend a day or two redoing. UDTs are by far better.

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We’re using all AOIs at the moment because we didn’t know any better when we did our projects. I really want to do a performance test on this, as we’ve certainly had issues with PLCs being overloaded, even the latest models like the L8x series (maybe L9x is out now?) get choked up (at 1s poll rate we see these at like 160-200% load factor :confused: ). @bschroeder said his LF reduced from 100% down to 10%, but it’d be good to get some solid figures to go off.

It is worth keeping in mind that the issue with AOIs is that EnableIn and EnableOut are forced to have “None” for external access. That is what breaks optimized reads from OPC drivers. You can set UDT members to no external access and break optimized reads for them, too. ):

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We did a pretty extensive bench testing on performance. Basically we took our AOI’s and dropped them into arrays of typical size for a plant. IE 100 motors, 500 DINs, 50 ains etc… and created corresponding tags in Ignition. Then started playing with different optimizations on the driver. Then modified the AOIs to have a UDT for SCADA tags, and the AOI for the PLC stuff and did the same thing. That gave us enough information and metrics to know which way to go.

Good luck! It’s a tedious and frustrating process. If AB would play ball a bit better with 3rd party vendors then this wouldn’t but such a bid deal.

BTW…we did see something very similar in WonderWare, we just didn’t have a good metric on how to read it.


Understatement! More like if AB would play ball period.

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They too busy trying to sell their crappy FactoryTrash software :unamused:

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