Logix 5 issues

Today I occured a problem that went like this;

- We emailed a copy of a Logix 5 program to a contractor, the copy was sent with my logix version 7.1

- Contractor opened the program with logix 4.1. His job was to modify the program and change from a PLC 5/15 to a PLC 5/20E.

- Contractor replaced processor and downloaded program changes. We had trouble trying to commission and found out that the data tables had been corrupted sometime during the conversion. I will have to check tommorrow but it appears that all of the "static" values in the tables had been changed to 0, whereas the ones that were written in the program were correct. All of the timer and counter presets, N and F variables were wrong.

Any idea where this could have gone wrong? I am assuming with the different versions of logix but I can't find anything in the release notes that might explain this.

As always thanks in advance

allscott said:

- Contractor opened the program with logix 4.1. Any idea where this could have gone wrong? I am assuming with the different versions of logix but I can't find anything in the release notes that might explain this.

As always thanks in advance

Click to expand...

proble is due to Program developed in higher version is opened in the lower version if you what to open in lower version convert it to *.AF5 file then you can open in lower version

When changng the processor type a message appears asking something to the effect of resizing the data files and/or clearing I/O. My guess is that the contractor cleared the I/O. Can't say that this did the trick as I don't think I have ever checked that box, but it is a possibility.

As mentioned, the older software revision would be my first guess as to the problem though.

OG

While playing and trying to fix the problem I also occured the "do you want to resize or clear the I/O" I don't understand this to begin with as the rack configuration as well as the data tables remained unchanged.

The contractor assured me that when he encountered that prompt he checked resize. I am not sure as to why they are being resized and didn't think that by simply resizing the data would change?

Normally, you don't want to resize data tables. If you do, the software will truncate the data tables to the last element in each file that is addressed by the logic. I guess it is supposed to be a quick and handy way to free up memory when changing processor types. In my experience, it has only served to take away spare addresses that I wanted to keep! I always uncheck that box, which I believe is checked by default.

Clearing the I/O image tables is usually a good idea. I have run into some surpirses when changing code, putting a smart (block transfer) module where digital I/O were, that were caused by leaving a few "ones" in the output image file for those slots.

AB has released a technote on this very issue.

Version 7 on is not backwards compatible with earlier versions of RSLogix. If you do open a version 7 program in an earlier version then the data tables will be empty or they will contian old values (eg, a program created in version 5 is opened and saved with changed data table values in version 7, then reopened in version 5, it will have the old values still. AB has released a file which you can copy into the RSLogix directory for version 7 which will make it backwards compatible if need be.

There is a lesson here somewhere. It would have probably cost less money to have purchased a tech connect support package and upgrade the old version of RSLogix.

Alaric said:

AB has released a technote on this very issue.

Version 7 on is not backwards compatible with earlier versions of RSLogix. If you do open a version 7 program in an earlier version then the data tables will be empty or they will contian old values (eg, a program created in version 5 is opened and saved with changed data table values in version 7, then reopened in version 5, it will have the old values still. AB has released a file which you can copy into the RSLogix directory for version 7 which will make it backwards compatible if need be.

There is a lesson here somewhere. It would have probably cost less money to have purchased a tech connect support package and upgrade the old version of RSLogix.

Click to expand...

Thanks, I found the same technote after digging. The problem we have is that we do have a tech connect contract and therefore are running the latest version of logix 5. The contractor we employed does more IT than PLC work (although is quite PLC capable). He does not have a tech connect because he doesn't do alot of PLC programming any more. He assumed, and I would have also, that if his version of logix would open the program that everyting was OK.

This cost us a day of commissioning time. Some lessons are learned the hard way.

Anyway, a heads up for anyone who wasn't aware of this issue.

I ran into the very same issue myself with RSLogix 5 about a year ago. The same thing can occur if you are running RSLogix 500 v7.0 and open an older version, it clears some of the timer and counter presets when you save it. IIRC correctly there was a patch released for it and I believe its not an issue with v7.1.

I incorrectly stated that the version my contractor was sent was version 7.1, in actuality it was sent with my counterparts laptop who, now that I think about it, I believe is still running 7.0.

I will check on monday and report back.