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

Ignition
1

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-NMGD1-CM1-F-COP-CM_531WF1_FR1/value

What I Want:

I have an Expression Tag called Tag Name inside the UDT. I want it to dynamically extract the device prefix from the path, which is the segment between the plant folder and the second dash:

Full Path Expected Output
.../KCW/N-KCW1-CL1-... N-KCW1-
.../GCW/W-GCW1-PH1-... W-GCW1-
.../NMGD/W-NMGD1-CM1-... W-NMGD1-

The plant folder name (KCW, GCW, NMGD etc.) and device suffix (-CL1, -CM1, -PH1) vary across instances, so the solution must be fully dynamic. Can it be done in ignition?

2

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.

3

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 tag inside the UDT i.e. {TagDescription}

4

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}, '/')[3,0], '-'), value()[0,0] + '-' + value()[1,0] + '-')

5

Hmm. No one should be without it. I would use:

transform(
    split(
        qvAt(
            where(
                split(
                    parsePath(tag('[.]refTag.sourceTagPath'))[0, 'tag'],
                    '/'
                ),
                it()[0] != 'value'
            ),
            -1,
            0
        ),
        '-'
    ),
    stringFormat(
        "%s-%s-",
        value()[0, 0],
        value()[1, 0]
    )
)

Presumably the UDT parameter will drive the source path for a reference tag. Place this expression tag adjacent to that reference tag.

Robust against varying tree depth, ignores present or absent /value, and varying length elements of the prefix.