Tag is Bad Quality in UDT

[TCARLSON]

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.

[nminchin]

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

[TCARLSON]

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.

[jlandwerlen]

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.

http://forum.inductiveautomation.com/t/cannot-read-some-tags-inside-rockwell-aoi/38393/13

Device Load Factor

Hello all, I just wanted to bring this back to life real quick because I have some questions regarding the newer L80 processors. I currently have 8,963 tags and I am using the Gb port on the front of the PLC solely for my Ignition server. My switch says I am hovering right around 2-2.1Mbps on the port for the PLC. My load factor is at 95%. Why is this so? Why am I not able to use at least half the bandwidth available to me? If this sounds like I don’t know what I am talking about, its because I…

[nminchin]

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 ). @bschroeder said his LF reduced from 100% down to 10%, but it'd be good to get some solid figures to go off.

Device Load Factor

We fought everything trying to be stubborn and use AOIs. It wasn’t until I did some serious testing and reading across multiple scada systems and in depth study and testing with Ignition that we changed to a udt and aoi system. 95% of our base tags are now in udts. One one specific system that has 150k tags plus we went from 90-103% load factor down to 10%. That was enough for me to know that AOIs are going to give you a bad time. Do AOIs work? Yep. But it is a shakey foundation to build a large…

[pturmel]

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. ):

[bschroeder]

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.

[lrose]

@bschroeder

AB would play ball a bit better with 3rd party vendors

Understatement! More like if AB would play ball period.