OPC alarm tag timing on Meta data

Ignition
1

Hello all, I'm going to try my best to explain this.

I have an OPC tag with an alarm. On this alarm under associated data I have a custom property that links to another OPC tag. I use this property to display some information on an alarm screen (this one specifically says which panel fired the action).

Now what I want with all this is for an alarm to happen and THEN grab extra OPC tag I have as a property to it.

This doesn't seem to be happening in this order, I'm guessing this has to do with OPC and that their is no guarantee on order of updated tags.

So I come here looking for some advice on this. I currently have 100's of alarms that have this, am I going to have to put a script somewhere to watch these tags and update the alarm database after an event has fired? Is their any easy trick here? Could active delay (assuming I don't care about seeing something for x amount of time) be a hacky solution? Also I'm curious the order of things happening when an alarm is fired, and how a property with another OPC tag would be read.

Any guidance or things to read into would be appreciated!

2

The binding for the alarm extra prop will be evaluated when the alarm goes active. Which will pick up the current value of tags in that binding. But as you noted, tags use OPC subscriptions, and those deliver values in pseudo-random order (tends to be the same order, mostly, but unpredictable and certainly no defined order).

The only out-of-the box solution is to use SQL Bridge transaction groups in OPC "Read" mode, with the alarm value as the trigger. That mode does a raw OPC read after the trigger to capture associated values into the DB. (Completely separate from alarming.)

You could script something similar with tag events doing such reads, but tag events are unsuitable for operations that reach out across the network. So, not safe for any significant quantity.