We use Ignition Edge to query values via OPC from an automation system. We then use MQTT Transmission to send MQTT messages to our broker.
There are around 600 tags that are queried at a regular interval, of these there are a number of tags where the value changes infrequently, we would like to run a script to restart the tag (the equivalent of right clicking the tag and selecting 'Restart Tag') on a regular interval ultimately to generate a MQTT message.
Is there a script available that would allow us to do this?
That shouldn't be necessary as that's the entire point of Sparkplug (hopefully you're using Sparkplug) is to only report on exception. So the initial value is only published at birth, then only changes to values are published afterwards. There is a rebirth tag on the Transmission module you can use to trigger a rebirth for Sparkplug, but if you're manually pushing values using MQTT scripting, you'll probably also have to script something to push these values out manually as well.
Edit: Also make sure you're using the primary host ID feature on both ends as this will guarantee a rebirth in the event of a comms loss on either end.
Thanks, yes I have been explaining that it is functioning as expected but there is an uneasiness that if a value has not changed for several days how do they know they value is still as last transmitted and not that the sensor or device is not updating the value.
Re sending the value does not solve that problem in my opinion, but seems to give them a level of comfort that it is working.
If the device goes down the tags will go bad quality. If the sensor goes down, then you need some signal in the PLC to know if there is "bad quality" coming from the sensor. Most sensors if analog will go high/low in the event of a failure, but I always program logic to detect comms failures, open loops, etc and send a bad quality tag to the HMI to indicate something is wrong.
Restarting a tag won't guarantee, nor indicate a sensor isn't working.