alias RSLogix 5000

Guys I know that this has been addressed before but after a search I come up empty handed. Can someone take me through the steps of creating an alias in RSLogix5000? I am new to the CompactLogix and I need to add some logic to this controller. I see alot of tags and alias, but I need to create a new one altogether.

Thanks

Let me restate the question. When creating new instructions in RSLogix5000 What is the steps to doing this? I know it is not as simple as dropping OTE and addressing it. from what I have read so far I see that I need to create a tag and an alias. I think that the alias is reference to a memory location or an address of a physical device. Here is another question, do I use the program tags sub file in the tree to see what tags are available or is that just what has been created thus far? and how do I add more for use in the program? I hope I am asking these questions right so you guys can understand.

Try this out in Google. Same search term gets over 100 hits from this site.
alias RSLogix 5000 sitelctalk.net/qanda

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When you add an I/O module to your I/O Configuration RSLogix5000 automatically creates all of the tags for that module.

You can use those tags as is. The downside though of course is that you did not name those tags. RSLogix has a default pattern for naming the tags and that is what you would have to use.

So after dropping your OTE instruction into the logic, you could assign a tag such as: Local:2:0.Data.4. That tag can be manually typed in or if you double-click on the question mark (tag placeholder) then you will see a drop-down field where you can go and manually pick the tag.

An alternative though would be to create an alias tag. This is a new tag that will be tied to an existing (Base) tag. Aliases can allow you to come up with a new name using your own naming pattern/scheme.

Aliases can be created several ways but one way would be to drop in your OTE instruction then type in the name of the tag you wish to use even if you haven't created it yet. Type it in then hit enter. Then right-click on it and at the top of the shortcut menu will be an option to create the new tag you just typed in. On the window that opens, change it from a Base tag to an Alias tag. In the "Alias For" field select the original base tag.

Now, if you are tying your logic to a strictly internal tag then an alias isn't necessary as that internal tag could be named anything we wanted when we created it. But that is not the case with I/O. So for example you don't need an alias for a timer, but using one for an I/O point would be useful.

There are alternatives to aliases but I wanted to address your specific questions.

OG

Thanks for the reply...

I am alittle confused, what if I wanted to use like B3:1/1 OTE to use as a condition bit internally with a comparitive instruction Like LIM. that way I can use the B3:1/1 through out my logic. I have figured out how to tie the OTE to the I/O Just havent figured out how to use addressing for the memory locations of the processor. can I add the additional tags for this.

an after thought...
does the tag reference the memory location? Can I see this location like the data table in RSLogix500?

There are no data files like in RSLogix500. If you need a binary tag, then you can create a (base) tag and name it whatever you like. For example you can create a BOOL tag and call it "coil_0". That IS the address. There is no other underlying memory location. You can then use "coil_0" as many times as needed just as you would use B3:1/1.

If you need another tag, then you can create another one and call it "coil_1" or whatever else you want to call it.

You can alse create a DINT tag named "coil" which is made up of 32 bits. You can address those bits as "coil.x" where x is the bit number from 0-31. This way you create one DINT tag and get 32 bool tags.

Or, you can create an array which is similar to a data file. You can create an array named "coil" and define it as any number of bits. BOOL arrays must be in multiples of 32. So you could create one array of 512 BOOLs and they would be addressed as "coil[x]" again where x is which bit (0-511) in the array. I picked 512 as an example, the array can be larger or smaller.

OG

Thanks alot. I am starting to understand this, and I think once I get it down I am going to like the RSLogix5000. Just used to what I have already learned.

Thanks again

Anytime! Once you get used to the 5000, you almost wanna cry when you have to go back to the SLC 500. Ok, it's not THAT bad.

OG

I am not really sure what the text in blue is, I assume that it is an alias. Am I wrong in assuming that and if so what is it and what does it mean if anything? why do I see it on every instruction through out the program except on what I have added? I know that I am doing somthing wrong can someone help me understand?

The item withing the '<>' signs is the thing the alias is an alias for. (Your 'LMRunToO' is an alias for 'OperatorPanel[10].0') I believe the '<??>' represents an alias which was created but not assigned to represent anything yet.

Hello Bernie

I was thinking that, not really sure how to assign it to represent something. Where do I do this at?

If you are just getting started with RSLogix 5000 you may want to look at some of the User Manuals / Docs which come with it. Many overlook this but Rockwell supplies a lot of manuals, even some I/O manuals.
From RSLogix 5000 select help, Online Books, Logix5000 Common Procedures.
Chapter 8 is Program Ladder Logic, Chapter 3 is Organize Tags. I think you will find a lot of valuable information here.


Kim

Thanks for the response Kim, I have been looking at the manual and this tag and alias stuff is just kicking the **** out of me. I tend to be a more visual person. you know, show me and I understand type.

As Bernie said the question marks are due to the alias point to a tag that has not been defined.
Example: If your Alias is "Trouble100" and it is aliased to "DriveFault". RSLogix will allow you to create the alias but it will show up as question mark until you have created tagname "DriveFault".
Create tagname "DriveFault" and set its type as bool.

Kim

I'm at home right now, no access to RSLogix500 but I'll try. Right click on the alias name (it looks like 'Double100' - the arrow is covering part). You should get a list of things which has, at the top, 'New' and the alias name. Click on that. In the opened box you can assign which portion of the program this alias belongs to ('controller' if you want an HMI to be able to see it) and a window where you can brouse to items in your controller. When you find it then select it then accept the alias assignment.

Alias Screen shots

Hope this helps
Couldn't upload bmp's due to file size.