RSlogix5000 and Alias Editing

JoseM

Member
Join Date
Jul 2011
Location
Texas
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I have a Modbus alias associated to a Tag on RSLogix5000 program that I want to change. Can I do this while online? If so how do i go about doing it?

I don't want to stop the PLC to do a download, too many liabilities.

Jose
 
While you can change the tag name while online and even delete it if it is unused, you cannot change the alias information or anything to do with the memory size.

You can create a new tag though.

OG
 
To expand on OG's post - you can create a new tag, then edit your code to look at the new tag instead of the old - then when all logic references of the old tag have been removed, you can delete the old tag.
 
So, I can not take a tag I created and change the alias that is associated to it, correct.

You are saying that if I create a new tag and associate an alias to it, can be done online.

This tag I'm trying to modify is tied to a big "Factory Talk View SE" project and I don't want to cause a disruption to the system.
 
I see the problem, the tag is accessed remotely, so you can't rename it without changing your RSView project.

But if you follow what I said to change the tag, by creating a new tag, changing all the logic references, and then delete the old tag - it is simply a case of renaming the new tag back to the old tag's name - this you can do online. This will restore FTView's access to the tag.

You will get a "disruption" to the system, as soon as you start editing the code that looks at the old tag, and the last step of renaming the new tag to old tag - choose a time when this will not be an issue, if available, it is not possible to do this seamlessly.
 
Just so I can be clear,

The tag use on the logic is "BHW_03_Running" and this tag is associated to this remote address, RIO2102_S1_MCMR.DATA.ReadData[44].2

What I need is RIO2102_S1_MCMR.DATA.ReadData[44].3 instead of the one from above.

So, if I create a tag called for example "BHW_03_Running_New" and associate the address RIO2102_S1_MCMR.DATA.ReadData[44].3 to it, how can I replace the old tag "BHW_03_Running" with the new tag "BHW_03_Running_New" in the entire program. Do I need to do run by run or does a "Find and Replace" function exist on RSLogix5000.

Lets say that I'm successful at changing the tag to the new one, communication is going to be disrupted to the FTV project, correct. Then I go to the "Controller Tags" area on RSLogix5000, delete the old tag and then edit the name of the new tag back to the old name.
 
and then edit the name of the new tag back to the old name.
I don't think you can do this step while online to a tag currently in use.

Just to summarize (as I see it) - Current Status:

Alias -> Target

BHW_03_Running -> RIO2102_S1_MCMR.DATA.ReadData[44].2

Desired

BHW_03_Running -> RIO2102_S1_MCMR.DATA.ReadData[44].3

Step 1 - Create

BHW_03_Running_New -> RIO2102_S1_MCMR.DATA.ReadData[44].2

Step 2 - Replace

Replace each BHW_03_Running with BHW_03_Running_New

This may very well be an individual 'Find / Online Edit' operation. I don't think the automated 'Find/Replace' is available online. Though the 'cross-reference' on that individual tag gives you a handy table to choose from. Come back to the table and choose 'refresh' after each edit. During this process the logic is still dealing with the status of the same point, just using different aliases.

Step 3 - Modify

Since it's now not being used you may be able to directly change the alias target for BHW_03_Running or you may have to delete and re-create it. While deleted your display system will complain.

Step 4 - Replace again

Replace each BHW_03_Running_New with BHW_03_Running

Again the 'cross reference' should make this faster. But be aware that while doing this replacement your code will be dealing with the status of two different points. Make sure this won't have bad consequences.

When done you can delete BHW_03_Running_New.


Good luck.
 
Last edited:
Thank you for your response Bernie. That procedure is going to work great and I just thought about something. The current alias,

BHW_03_Running ---> RIO2102_S1_MCMR.DATA.ReadData[44].2

is not changing state on the PLC code because it is an address that don't have any use.

So when I do the change you suggest Bennie, I should not have any negative impact. There are only two locations on the code where BHW_03_Running is being used.
 
I don't think you can do this step while online to a tag currently in use. (1)

Just to summarize (as I see it) - Current Status:

Alias -> Target

BHW_03_Running -> RIO2102_S1_MCMR.DATA.ReadData[44].2

Desired

BHW_03_Running -> RIO2102_S1_MCMR.DATA.ReadData[44].3

Step 1 - Create

BHW_03_Running_New -> RIO2102_S1_MCMR.DATA.ReadData[44].2

Step 2 - Replace

Replace each BHW_03_Running with BHW_03_Running_New

This may very well be an individual 'Find / Online Edit' operation. I don't think the automated 'Find/Replace' is available online (2). Though the 'cross-reference' on that individual tag gives you a handy table to choose from. Come back to the table and choose 'refresh' after each edit. During this process the logic is still dealing with the status of the same point, just using different aliases. (2a)

Step 3 - Modify

Since it's now not being used you may be able to directly change the alias target for BHW_03_Running or you may have to delete and re-create it
(3). While deleted your display system will complain (4).

Step 4 - Replace again

Replace each BHW_03_Running_New with BHW_03_Running (5)


Again the 'cross reference' should make this faster. But be aware that while doing this replacement your code will be dealing with the status of two different points. Make sure this won't have bad consequences.

When done you can delete BHW_03_Running_New.


Good luck.

(1) Yes, you can change a tagname online, while the processor is running.

(2) Find/Replace in not available online, using the cross-reference is a sound idea, and I should have mentioned it.

(2a) This is incorrect, the logic is now seeing the data from
RIO2102_S1_MCMR.DATA.ReadData[44].2 via the new alias
.

(3)
Even though BHW_Running is no longer in use, you cannot change the "structure" of it online - that is, you cannot change what it is an alias for - you have to delete it.

(4) The display system will not exactly "complain" about the tag until it is deleted, but it will be displaying incorrectly (a static value) as soon as the destructive instruction is edited (i.e. the instruction writing the value of the tag). For minimal impact, edit this instruction last.

(5) This step is not necessary - after deleting BHW_Running, and your code is now running with BHW_Running_New, sinmply rename BHW_Running_New to BHW_Running.
 
Last edited:

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