This lesson is part of the Tags in Ignition course. You can browse the rest of the lessons below.


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Tag Quality and Overlays


Learn how Tag quality can be used to easily recognize and diagnose many kinds of Tag problems.

Video recorded using: Ignition 8.0


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[00:00] Since tags in Ignition can represent data coming from real world devices and databases, there can of course be real world problems that interrupt the flow of data. To account for this all Ignition tags have an associated quality, which essentially dictates how much we can trust the value on the tag. A tag with a quality other than good is generally untrustworthy as it means something in the data flow has gone wrong. There are many reasons for bad quality on a tag including network disconnections, overloaded devices, and tag configuration issues. To demonstrate what I mean I've configured a couple tags here in the tag browser. And these tags are both pointed at a real world device. Now everything on these tags seems to be going just fine, as we can see we're getting values coming through pretty regularly. And if I expand one of my tags here, we see that the quality of my tag is good. But let's supposed I change this, what I'm going to do is break the network connection to my device, which will cause this tag to stop receiving new values. So now having severed the connection we can see a couple of changes made to our tag. For one the value of the tag has stopped updating as we would expect, and the quality on our tag has been set to bad. Now there are many possible quality values, you can find a full description of each possible quality in our user manual. Note as well that an icon has appeared next to my value in the tag browser. An icon will appear like this in the tag browser anytime that a tag is not good quality. If I hover over the icon it will show me the current quality on the tag, but it's worth noting that there are other ways to find out that this tag has bad quality. To demonstrate I have a vision window here, and let's say I'm representing this tag on the Vision window in some way. So I'm going to drag it in from the tag browser, and let's set it up as an LED display. We can see that the LED display component has an overlay, indicating that an associated tag has bad quality. Though we're currently viewing this in the designer, any open Vision clients or perspective sessions, would similarly indicate that there's a problem with the tag. So now if reinitialize my connection to the device, and we wait just a moment, we can see that the values are starting to come through again. The quality on our tag has changed back to good, and our LED display no longer has a red overlay.

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