New guy with a question

plcpart · May 5, 2012

Hello all. I am a electrical controls tech that does installs and trouble shooting of control systems involving PLC's. I am not a programmer but do have some understanding of how they work.

My question is, we removed a plc from a inservice system and now have some of the parts from it in our possession including the CPU. My uncle who is the company owner and my boss has considered selling these parts but he is worried that the CPU may have propriortary info stored on it. We have no way of deleting the program. It has been powered down now for a week or so and the battery was unplugged.
It is a Modicon 140 CPU 534 14B. Would there be any other info on it other than the ladder logic? Is there anything to worry about?

jrwb4gbm · May 5, 2012

Welcome to the forum!
I found this in a manual:
When the controller is in operation, the batteries can be replaced at any time.
Note: When the controller is powered OFF, battery replacement can be done
without RAM loss only when a second functioning battery is installed.

Based on that info, I would say that the program should be gone if all batteries are removed and powered off for a period of time as you indicated. I would suggest powering it back up to see if there are some error codes flashing and that the run indicator LED is off.

Paullys50 · May 5, 2012

plcpart said:
Hello all. I am a electrical controls tech that does installs and trouble shooting of control systems involving PLC's. I am not a programmer but do have some understanding of how they work.

My question is, we removed a plc from a inservice system and now have some of the parts from it in our possession including the CPU. My uncle who is the company owner and my boss has considered selling these parts but he is worried that the CPU may have propriortary info stored on it. We have no way of deleting the program. It has been powered down now for a week or so and the battery was unplugged.
It is a Modicon 140 CPU 534 14B. Would there be any other info on it other than the ladder logic? Is there anything to worry about?

The odds of selling the CPU to someone who is actively looking for "propritary" info still contained within the CPU is slim to none. Keep in mind an "upload" typically won't contain comments or descriptions so the code will be very cryptic.

If your uncle is that paranoid, the profit they might lose by not selling it is surely CHEAP insurance of their concern. Better too to take a hammer to it and toss the pieces into the trash can then take the risk.

Tharon · May 5, 2012

I personally have uploaded files from processors I received used just to see if/what it might have been prior to my use.

Sometimes I can see what it was used for by the way the code was laid out, and in the case of the AB processors they retain their processor name which sometimes is meaningful.

But overall, the information I've pulled out of used PLCs is pretty useless.

plcpart · May 5, 2012

Thanx for all the info everyone. It really has helped. I plan to attend some basic programming training just to understand a little better the items that I am wiring. Not an engineer so I guess I will never be a full time programmer but it all is still interesting to me.

Clay B. · May 5, 2012

Why not just keep the PLC and use it as a trainer. I acquired alot of PLCs this way that landed in my garage so I could play and learn with them.

I really would not worry about someone getting the code as someone already stated without comments the program would be difficult to read and without the the machine it went into almost impossible to decifer.

plcpart · May 6, 2012

Thanx everyone. Great advise. Thanx for taking the time to help a new guy. Most forums seem to ignore new people.

Mickey · May 6, 2012

Not an engineer so I guess I will never be a full time programmer but it all is still interesting to me.

You don't need to be an engineer to program, many here are not. Just a sense of humor.

New guy with a question

plcpart

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jrwb4gbm

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Paullys50

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Tharon

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plcpart

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Clay B.

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plcpart

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Mickey

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