I am using Ignition 8.3.6 with MQTT Engine. I have a UDT with a Parameters folder containing tag1 which holds an MQTT tag path like: [MQTT Engine]Mimics/iotdata/KCW/N-KCW1-CL1-J-PV-CL_471FN7_KW/value [MQTT Engine]Mimics/iotdata/GCW/W-GCW1-PH1-X-PV-J1P63_X2/value [MQTT Engine]Mimics/iotdata/NMGD/W…

[image] nminchin: without Phil's Integration Toolkit Hmm. No one should be without it. I would use: transform( split( qvAt( where( split( parsePath(tag('[.]refTag.sourceTagPath'))[0, 'tag'], '/' …

yes. split and indexOf will need to become your friends. Check those expression functions out, and you should be able to get it worked out.

This is honestly not sustainable and will cause a nightmare further down the line when a site is introduced that does not have the exact same tag pathing. I would instead add more parameters to the UDT and include a TagName or TagDescription parameter that could then be referenced in an expression …

[image] prasoon: [MQTT Engine]Mimics/iotdata/KCW/N-KCW1-CL1-J-PV-CL_471FN7_KW/value This is ugly without Phil's Integration Toolkit module.. But here goes split(split({value}, '/')[3,0]), '-')[0,0] + '-' + split(split({value}, '/')[3,0]), '-')[1,0] + '-' Or transform(split(split({value}, …

[image] pturmel: Hmm. No one should be without it. I would use: transform( split( qvAt( where( split( parsePath(tag('[.]refTag.sourceTagPath'))[0, 'tag'], '/' ), it()[0] != 'value' …

[image] prasoon: applied your code You didn't use my parsePath() function at all. (Not so robust without it.) Did you install my Integration Toolkit module? Won't work without it. And for some versions of v8.1, a gateway restart is needed for the functions to work in expression tags.

[image] pturmel: You didn't use my parsePath() function at all. (Not so robust without it.) Did you install my Integration Toolkit module? Won't work without it. And for some versions of v8.1, a gateway restart is needed for the functions to work in expression tags. Hi Phil, Thank you for y…

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Thanks a lot, your script works after installing the tool.

Extract Dynamic Substring from MQTT Tag Path in UDT Expression Tag Ignition 8.3.6

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pturmel May 21, 2026, 4:51pm 9

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