ControlLogix5000: Bit Names

Colt Hero

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Join Date
Apr 2015
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USA - Southeast (but from Northeast)
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109
If I define an INT or DINT for, say ... a BitFlag word ... is there any way to name each bit in that flagword with a unique name? It would seem like you'd be able to do this with an alias, but when I click on that column it doesn't let me type a name in. All it seems to let me do is access each bit by FlagWord.0, FlagWord.1, etc.

Is this the best I can do? That's not very descriptive.
 
I had to do that just this morning. Just do what jstolaruk said and create a UDT. Go to Data Types>User Defined in the controller organizer. Here you can create your own data type and add uniquely named tags under it. Here is a picture I attached of the one I made this morning.
 
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You can describe each of the bits with a description if you do not want to create a UDT. Downside is it will not be a tag, but if you are using Studio 5000 you may save the descriptions in the controller.
 
Since the new multi-core Logix processors include an additional on-board memory chip, starting with Version 21 they also now all support saving routine comments and descriptions into the processor itself.
 
Since the new multi-core Logix processors include an additional on-board memory chip, starting with Version 21 they also now all support saving routine comments and descriptions into the processor itself.

My bad, on the earlier versions it felt really slow downloading the extended properties so I unchecked that option.
 
Looks like I'm running with RSLogix5000 ver 20.04, CPR 9 SR 5?

OK - I can see that I can edit the "Description" field, and that helps, but I'd want better than that ... I want it to show up in-line, with the logic.

Ken Moore: doesn't your way result in a bunch of 'free-agent' tags possibly scattered about the tag list, pointing back to your bit array? Is there an advantage to that over a UDT, which sounds to me like a "C" Structure (which is what I'd rather be using)...???

alanze: For some reason, I can't see your attached image.

===========

UPDATE: The UDT worked fabulously (once I realized I had to re-select the Data Type on my original tag)! That's exactly what I wanted. Thank You! Even started the description field with " : " so that the inline instruction comment reads nicely...
 
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maybe I'm misunderstanding what you're asking - but see if the screenshot below helps ...

so - unless I'm misunderstanding the question - the answer is "yes - you CAN assign an alias to a specific bit within a DINT" ...


.

BIT_ALIAS.PNG
 
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RonJohn:

That overlay seems kind of clunky to me. I get what he's trying to do (I think), but the system doesn't seem to like XML comments, I guess.

Ron:

Yeah, what you're describing sounds like a take-off on what Ken suggested ... except your're doing it with a DINT and he was doing it with an array.

I was just trying to give the individual bits of a DINT individual names, and after creating the DINT didn't see any way to do it. So I first thought of "aliasing", which is possible (apparently), but I think the UDT is better because it keeps everything together in one package (as opposed to creating alias tags pointing back to a DINT that could end up scattered anywhere in your tag list).

Is there any downside to going with the UDT over the aliasing, or is it just a "preference" thing?

Another question:

The Tag List is purely alphabetical, right? This isn't like building a data segment in "C" where you can put things wherever you want, right? So if you want your "like" tags to be clustered neatly together in your tag list, you have to name them hierarchically, correct?
 
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