ControlLogix Tag names & wire#'s

[dogleg43]

Need to know how others are coming up with their I/O wire#'s when using Rockwell ControlLogix PLC's. We're starting to do more of these systems and need a wire # that is easily searchable in the program and also works for as a wire label (it's hard to print more than 9 characters on most wire tags).

We tried to # wires similar to a PLC-5 (example: I00114 - input-rack-slot-bit) but that didn't work because we started to have duplicate #'s. We had I/O modules in the rack with the ControlLogix PLC and also a DeviceNet rack in another panel. We ended up with two rack 1's, two slot 1's,etc.

 

[dbaird]

For the Devicenet ones could you use the node number? Or set it to a higher node so numbers don't conflict?


David Baird
mrbaird@hotmail.com

Sr Controls Engineer

EET degree.

Journeyman Electrician.

 

[rdub]

With the standard A-B Micro/SLC addressing in mind, what I do is create an "alias" tag for each I/O module in the rack and I give it a name that closely resembles the old micro/SLC addressing scheme. For example, if I have a 16 point input module in slot 3, the Control Logix database will tag is as "Local:3:I.Data(.0 thru .15). Not very helpful when writing a program or trying to assign a wire label. I will create a new tag (DINT) with the name "I3", click on the alias box, and in the "alias for" box, you enter "Local:3:I.Data". Now to address a point on the module, say slot 3, input 7, instead of typing "Local:3:I.Data.7", you now type "I3.7". You can use "I3.7" as the wire tag and as a reference in your drawings.

 

[dogleg43]

rdub - thanks for the example. From an electricians perspective, many will have difficulty making the leap from "I3.7" to "Local:3:I.Data.7".

 

[rdub]

I have also used this technique with DeviceNet installations. First assume my DeviceNet module is in slot 1. Using RSNetworx, I assign my node 1 I/O to word 11, node 2 I/O to word 12, etc... Again, I create an "alias" tag in the processor called "I111" and make it an alias for "Local:1:I.Data[11]". Now when programming, all I have to use is "I111.0", "I111.1", etc... As long as the DeviceNet installation isn't too large, this will work fine.

 

[EEAutomEng]

I just did a project with ControlLogix and our customer had us use their plant standard. Dogleg had a good point. Try this:

"Local:3:I.Data.7" would have a wire tagged as L:3:I.07