ControlLogix Alias issue

[dbmtaylor]

I am working on a controllogix PLC and creating a new Tag ( Alias for a local 32 way Output ) , when I go to create the tag using the popup box, and assigning the Alias to the local Output it shows me that the output I want is been used, but when go directly to the local tag and do a cross reference it not been used, and look like the last three on the card are the same.

 

[daba]

I am working on a controllogix PLC and creating a new Tag ( Alias for a local 32 way Output ) , when I go to create the tag using the popup box, and assigning the Alias to the local Output it shows me that the output I want is been used, but when go directly to the local tag and do a cross reference it not been used, and look like the last three on the card are the same.

The cross-reference facility can be used "By Logic", "By Tag", and "Tag Hierarchy" - look at the bottom of the Cross-Ref screen for the tabs....

If you don't see any "Logic" references, there could still be "Tag" references, e.g. someone had previously set-up an alias, and never used it.

You might even discover "the last three on the card" are aliased by tags called "Spare_nn", lol, I've seen it happen....

 

[dbmtaylor]

Thanks a lot that was a big help

 

[daba]

Thanks a lot that was a big help

Please tell...

what did you find ?
was I right ?
"spare_nn" or similar, or obsolete I/O ?

suspense is killing me....

 

[dbmtaylor]

Yes thanks I did find it and you where right it was an obsolete I/O someone had remove from program but didn't delete and old tag.
I appreciate you time and help

 

[labeledas]

that spare_nn has caught me too, not sure if it considered good practice or not I have always just left spares untagged

 

[daba]

that spare_nn has caught me too, not sure if it considered good practice or not I have always just left spares untagged

My thoughts exactly, no need to tag anything you aren't using or referencing.