SLC 500 Remap I/O Possible?

I have a problem with an SLC 500 1747-L40A and a quick / temporary solution would be to remap an apparently damaged output to a different output point...

Is that even possible (in runtime)??? The module is mounted with a 1747 DTAM... Please consider I'm no expert in SLC or any PLC platform, but I certainly understand the whole system and have dealed with this module a couple of weeks already...

If not possible in runtime, what would be the easiest way of doing this??? Consider I don't have the development tools at hand because this was a total random / last minute problem that occurred in a client's plant...

Thanks a lot!!!

Depending on how it was programmed, it could be really easy or somewhat more involved. Usually it's good programming practice to use inputs and outputs (real I/O) only once in the program. So to change a "bad" out should only require one change in the program. Of course you have to rewire the output to another point.

But in your case, the L40A doesn't support online programming. The change would have to be made in program mode or made and downloaded to the processor.

Consider I don't have the development tools at hand

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The RSLogix programming package - or the old hand-held programmer - would be necessary.

EDIT: First, you'll need the development tools (RSLogix 500 & RSLinx)

But when you say you have been dealing with it for some time...please explain further. Solid state output points don't go bad and then start working again, but relay outputs can do that. Are you certain that the output point is faulty (not trying to insult, just making sure based on your professed experience with PLCs).

EDIT: Yours does have relay outputs, so intermittent functioning is possible. If you have a whole spare unit and the existing one has it's program burned to EEPROM, you could replace the entire thing, but you may run a small risk of losing data or reverting the program back to its last state as burned to the EEPROM. Don't do this unless you are sure you have a valid program on EEPROM. Leave the battery in the old one too if you do this so you can back track without losing the program that is running right now. This method could avoid the need for RSLogix/Linx.

Okay, as for moving I/O in a SLC program with RSLogix:
The simplest way to do this is offline and then download.

Offline you can Find (example) O:2.3 and replace it with O:2.4 and even copy or move the descriptions at the same time with a radio button option.

In a modular SLC you can easily move all the points on a whole 16 point card by find and replace at the word level too:

Find What:
O:8
Replace With:
O:9

Sometimes you must be careful with indirect addressing and with file level commands, but should not be present for real I/O with the exception of perhaps copying to HMI bits for display.

That's an old "all in one" unit. I think they could have an additional two discrete module. So it could be necessary to replace the whole unit if no output spare are available.

OkiePC said:

But when you say you have been dealing with it for some time...please explain further. Solid state output points don't go bad and then start working again, but relay outputs can do that. Are you certain that the output point is faulty (not trying to insult, just making sure based on your professed experience with PLCs).

Click to expand...

What I meant is that I'm new in the world of PLCs, but I've been studying this SLC 500 1747-L40A for a couple of days/weeks... The damaged module has always been damaged since last week and never started working again... And the client has other modules also damaged (for different reasons) and I checked them before internally looking for damaged points (once I even removed a darlington IC and relays and tested in protoboard) and always got to dead end (relay ok + darlington IC ok = dead end because the IC sending the signals to darlington IC is some microprocessor that I can't even find a datasheet, probably some custom AB processor)... But since they had working replacements SLCs I didn't put much effort since this system must definitely be replaced for newer hardware and software... But now it failed again, and the client was supposed to have a replacement ready just in case, but they didn't and need a quick solution to this problem...

I've never done serious PLC programming but I've done a loooot of embedded programming (microcontroller and microprocessors) and PC programming too... So, that embedded programming experience somehow helps...

Right now, I only have damaged units and this remapping would solve the problem at least for a while since the whole system is redesigned and replaced...

Maybe you could help me with other issues more explained in this thread

jkerekes said:

That's an old "all in one" unit. I think they could have an additional two discrete module. So it could be necessary to replace the whole unit if no output spare are available.

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Indeed it has two more modules: A 16 input module and a 4 output modules... Honestly, all outputs are used, but I could replace a less important output (one that may be handled "manually" or simply ignored by now, like one of the horn outputs...