Access Nested AOIs in ControlLogix PLC with Wonderware

[abishur]

Using Archestra 2014 I'm trying to access an tag in a ControlLogix L75 with firmware 21.xx

I can access all the data in the top level of the Add-on instruction, but all my alarms are handled as a second Add-on instruction. So in the end the tag in the plc is

Tagname.Alarm[0].Status

Does anyone know how to access the data in the nested AOI?

 

[bernie_carlton]

Is 'tagname' local to the AOI (which I doubt) or is its scope higher, possibly on the controller level?

The processing may be in the AOI but the tag is probably external to it.

It wouldn't make sense to have an internal tag if the status of the alarm has to be used external to the AOI.

Or is 'tagname' the name of the higher level AOI? If so what is the scope of the 'Alarm' array?

 

[abishur]

Yes Tagname is an Add-on Instruction datatype at the controller level and has read/write access.

Alarm[0] is an array of Alarm Add-on Instructions and is a member of the Tagname Add-on instruction. It also has read/write access

Status is a boolean tag member of the Alarm Add-on Instruction datatype. It had read only access.

I've used this setup at several other sites using FactoryTalk view Studio SE, but now I'm starting a project using Wonderware as the top end and can't seem to get it going.

 

[bernie_carlton]

It sounds like a Wonderware specific issue then if you have accessed the tag using other platforms. Sorry I can't help.

 

[Paullys50]

It's probably a WW issue, v21 changes how information is accessed from the PLC so drivers have to get re-written. I know this because it's the same story with Ignition. Their v21 driver seems have it all worked out now, but the first releases of the driver had similar difficulties with accessing tags in AOIs/UDTs.

I would contact WW to see what the latest DA Server they recommend, and if they have released any patches to their drivers to improve it.