keep value

Simple question:

I have made some changes in a SLC 5/05 offline and want to download it again. How do i keep the value that are in the processor and not the old on in my program

Upload first then edit.

The other way is to do the editing online.

Alan

Hojland said:

Simple question:

I have made some changes in a SLC 5/05 offline and want to download it again. How do i keep the value that are in the processor and not the old on in my program

Click to expand...

Simple answer: you can't.

This is one of the biggest drawbacks of Allen-Bradley SLC/Micrologix. (I don't know how Control/CompactLogix operates in this regard.) You can't selectively download program and data files; it's all or nothing. Online editing is an option but is not feasible for large changes or if you want to work in the peace of your office. You can and should do an upload first, of course, but if the data tables change in the meantime, you're sunk.

If you have an application with a lot of retentive data values, it's helpful to offload this data to a device such as a Red Lion G3, which can save data in flash memory or even to a CompactFlash card if necessary. Then you can download to the PLC with no worries.

With the PLC5, you are allowed to download logic without overwriting data table RAM. I don't believe that this option is available for SLC processors, but there is still a solution.

Simply open two instances of RSLogix500. With one instance, go online with the current version of the program. With the other instance, open your new, offline version of the program.

Now, select the logic that has been changed in the offline version, copy it and paste it into the online program. Then delete the old logic that the new logic replaces. Now, accept the changes and test and assemble.

I do this on a regular basis when I have to make a significant change in a program for a process that cannot be halted. Search and replace capability is not available in online mode, and editing is much quicker and easier when offline than when online.

Do your changes in the office, then go to machine upload program and save, then do a file compare and change the data tables in the modified project to match the uploaded file.

Alan

alan_505 said:

Do your changes in the office, then go to machine upload program and save, then do a file compare and change the data tables in the modified project to match the uploaded file.

Alan

Click to expand...

With this method, you still only get a snapshot of the data table status. Besides, you can't download the new program without stopping the processor.