alias description pass-thru question

I've created an application and I'm at the point where I am aliasing some programming boolean tags to actual I/O tags. I went through all my actual I/O tags and filled in the description. I figured when I aliased my programming tags to my actual I/O tags the description from the aliased tag would get passed through. I have no description in the tag I created in my program because I figured it would show up when I aliased my actual I/O tag. I looked at the options and pass-thru is enabled. I'm using RS5000 V17. Am I missing something because After I complete the alias, there is still no description. The tag I have my alias pointed to has a description. Why isn't the description showing up in my programmed tag?

Hi, johnfarrugi

Personally I wouldn't put any descriptions at all to actual I/O tags.

I would put those descriptions to the alias tags which point to the I/O.

One of the usefull features of alias tags is that you can write all of your application code in advance of knowing the actual I/O - perhaps it's someone elses job to assign it - by creating (initially) your plant I/O refereneces as internal tags - boolean for digital I/O, and real for analog I/O.

Only at the point when the real I/O is finally assigned could you then edit the internal tags to alias tags to reflect the actual I/O. And the simplest way of doing this is to export the tag database to a CVS file and use Excel to change them to alias tags.

It is also a great idea to put your I/O alias tags in the "Program" scope - i.e. put them in the Program Tags database for the Program you are working in. It makes it a whole lot tidier if you want to copy/paste the program to replicate it for a similar application.

Hope this helps.

Are you creating Alias tags defined in Controller/Program Tags or are you programmatically creating aliases?

OG

I have already created the program in advance. All my "Alias" tags are located in the program scope and not in the controller scope. I didn't initially assign descriptions to my alias tags because I figured that once I aliased them to real I/O the description from the real I/O would get pass-thru but I guess this doesn't happen.
I like to put descriptions on actual I/O because when there is a problem in the field and electrician or who ever will look at the prox which they are having a problem with, find the address labeled on the cable and go the the actual I/O and search the program. browsing the actual I/O with description will also help in trouble shooting.
Does this mean I need to copy the descriptions from my actual I/O to my alias tags?

Pass-thru descriptions will not pass from Base Tags to any tags which alias them. Pass-thru is for UDT tags, where the documentation in the UDT is used on any tag created from the UDT that is not commented directly.

I still stand by my "not documenting actual I/O" in spite of your comments about tech's wanting to trace through the logic.

Show them how to do croos-references on I/O tags, all occurrances, including any that are aliased to the I/O tag, will show up in the x-ref results window. Hopefully, there will be only one tag aliased to the I/O point.

Click on any of these "back-alias" display lines to take you to the logic where you will see the documented alias tag.

Keeping your actual I/O uncommented allows for any re-wiring or re-structuring of I/O to take place without having to do a raft of re-documentation.

Also make sure you have the "Tools"->"Options"->"Ladder Editor Display" : "Show Tag Alias Information" checkbox ticked. It makes life much easier by showing what is real-world I/O and not internal tags.

Pass-thru DOES allow you to document the Base I/O tags and have that description pass-thru to undocumented Alias Tags.



OG

I am a big fan of documenting real IO. It is a real pain in the butt when I get called to a job somewhere and the IO is not documented. I know you can track it back through but why should you have to. In my opinion not documenting the IO because you may wish to change something in the future is like not washing because you will only get dirty again.
For me it is a moot point to document aliased IO as I never use that style. I am a bigger fan of mapping the real IO into a UDT for each machine or process.
Regards Alan Case

whoops...

I stand corrected OG ! Time to do my lines...

Must remember to check my advice before posting.
Must remember to check my advice before posting.
Must remember to check my advice before posting.
Must remember to check my advice before posting.
Must remember to check my advice before posting.

Anyway - you have included the proof in the screen-shot, and that should answer the OP's query.

The problem with making a definitive Yes or No response is there is always someone out to prove you wrong!!

OG