Mapping integer file

[Mwils]

I'm in the process upgrading and rss project and going through the program adding descriptions to the operation I've come across an integer file that have values but are not found in any routines linking them to the program or in the panelview tag data base. I'm just unsure what to do with them.

 

[JaxGTO]

Make sure they are not being indirectly addressed like N100[N7:0]. Where N100 is the integer file you think is not being used. SLC also has the ability to index across file boundaries. I don't remember if a SLC can also indirect files like a PLC 5 but it would look something like N[N7:0]:[N7:1] where N7:0=100 for N100 and N7:1 would point to the word in the file.

 

[OkiePC]

Also look to see if they're assigned as channel diagnostic files to one of the PLC communication channels.

If you have a Standard or Pro version of RSLogix 500, the Usage button on the data table view will show an "X" for each bit or number that is in use in the ladder file and a "." for data that is not in use.

This can be deceptive for cases where indirect addressing is in play as JaxGTO explained. This is because the editor doesn't try to predict or assume all the possible values inside those square brackets. If in doubt, I will do a search for "[" to see if there is any indirection at all in a RSLogix 5/500 project. It also cannot know all the addresses that might be written from or read by a remote device like an HMI or another PLC so it is a good idea to examine all the other possible or likely usages on the whole controls network.

 

[Operaghost]

Sometimes the file name can clue you in to how it is being used. For example, if it is being used as a diagnostic file as OkiePC mentioned, then the file would be automatically named "CH0 DIAG" or "CH1 DIAG". The Usage for these would all show as unused, but the name tells me their purpose.

As for the Usage function, if you see a letter then that indicates it is in use. You might see "F" in the FW column if the addresses are used by a file type instruction (like a Bit Shift). You might see an FW if a word within that file is being used. Or you might see "X" if it is used by a Word or Bit type instruction. The "F" and "FW" are mainly seen when viewing usage with binary files.

And of course, it is entirely possible that the file is not being used. Maybe it was being used at one point, but they deleted the code and the data remained.

OG

 

[Nova5]

Does the data change? Could other PLCs be writing to it?

 

[Mwils]

Thanks for all of the suggestions. The file/routine is for a counter range (start/end 1 and start/end 2) specifications to spread topping, the integers that have numbers are listed as not being used in the data table and the counter reset is listed and numbers that I'm seeing are for more then max counter reset. I've searched for any indirect addresses linking it to them but I'm not finding it so as of right now I'm assuming there not being used. But thanks again.

 

[James Mcquade]

the integers could possibly be used for a recipe.
they may be accessed from a panelview terminal or scada (wonderware, rsview, other) look to see if there is an R6 file number being used (slc500 for example).
hope this helps,
james

 

[Nova5]

Thanks for all of the suggestions. The file/routine is for a counter range (start/end 1 and start/end 2) specifications to spread topping, the integers that have numbers are listed as not being used in the data table and the counter reset is listed and numbers that I'm seeing are for more then max counter reset. I've searched for any indirect addresses linking it to them but I'm not finding it so as of right now I'm assuming there not being used. But thanks again.

Usage can be misleading as it only shows whats in us by the PLC. it could as said above be a recipe storage. Read and written to from a HMI alone. the PLC would not show that as in use because it isn't using it itself.