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Old August 9th, 2016, 04:33 PM   #1
jfd7851
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MSG Instruction via Structured Text

Hello everyone,
I am using a Control Logix L73 controller, with a motor that runs on Ethernet IP protocol.

I currently have an AOI for a motor that is in structured text. The manufacturer of the motor allows you to download a data type off of their own software where the initial IP Address and settings are configured. The data type is limiting, as you have to choose what parameters to include on the data type and their are limited spaces.

To get more useful information out of this motor, I have been investigating using the MSG instructions (Get Attribute Single, CIP Generic) to pull the other data that wasn't included on the data type. I have been successful at doing this when the message is triggered and defined in a ladder logic sequence. My goal is to define the MSG instruction within a structured text environment so that after some development time it could be added into an AOI.

I understand that I can call a MSG instruction in structured text as MSG(Message Control Tag). I do not understand where within the MESSAGE datatype that the destination tag is defined (other than the configuration tab on the Ladder Logic instruction).

So far I have read the 'General Instructions Reference' multiple times, I've tried some 'hacky' methods to see if I could either :
a.) create the message instruction in a ladder logic script so that everything is defined and then delete the Ladder logic and call it from a structured text script.
b.) tried setting MSG(message control) = another tag in the environment and that did not work either.
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Old August 9th, 2016, 05:04 PM   #2
nhatsen
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Quote:
Originally Posted by jfd7851 View Post
I do not understand where within the MESSAGE datatype that the destination tag is defined
If you have in ST:
Code:
MSG(tagname);
Just right-click on the tagname. In the context menu, click on Configure "tagname": you'll get the same configuration popup used on ladder.

Update:

TN 67344 ControlLogix Message Example in Structured Text (Access Level TechConnect):
https://rockwellautomation.custhelp....d/67344/page/1

TN 45154 How do you configure a MSG in Structured Text? (Access Level TechConnect):
https://rockwellautomation.custhelp....d/45154/page/1
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Last edited by nhatsen; August 9th, 2016 at 05:20 PM.
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Old August 9th, 2016, 05:20 PM   #3
harryting
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I think OP is looking for the sub-tag string location where the destination tag is stored because OP want to use it in an AOI.

I can't find it either.
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Old August 9th, 2016, 05:49 PM   #4
jfd7851
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Thanks nhatsen and harryting for the prompt reply. I have been looking for both of the issues brought up. Now that I can specify the destination tag out of the structured text thanks to nhatsen, it doesn't seem to want to run the message instruction. I set up a IO task to test that has a structured text script that just has MSG(message control). Whenever I put the controller into Run, the enable bit doesn't set. I'll post if I get a solution or find where the destination tag is stored.
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Old August 9th, 2016, 05:50 PM   #5
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Yes, there's no LocalElement in the MESSAGE structure.

It would suppose a kind of indirect addressing by name, and I think it would be a little troublesome to implement... Or maybe I'm wrong.

UPDATE:

Another Technote

TN 117368 Why does .EN bit in MSG Stay True in Structured Text? (Access Level TechConnect):
https://rockwellautomation.custhelp....il/a_id/117368
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Last edited by nhatsen; August 9th, 2016 at 05:54 PM.
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Old August 10th, 2016, 11:15 AM   #6
jfd7851
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Update:
I was able to get the message to 'relay' up through our current AOI that is in structured text and pull the information. Thanks for the help. Moving on to trying to get the whole instance of the object rather than each individual attribute.. Anyways, thanks again.
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