addressing of national plc

we have plc (national pc pl 40 m ) and we have the program

in ladder but addressing and function is not known for me

please help me

Mas 2000,

This is a common problem. I can not give you the answer, only some suggestions on how to create a new set of address labels and rung comments.

1. Search for old software copies of the program. Contact the machine builder or the machine PLC programmer. If not available then:
2. Search for old printed copies of the program, that have the address symbols, comments, and other information. If not available, then:
3. Search for wiring drawings and schematics of the machine or process, then start creating new PLC program symbols and comments. If not available, you are reaching the end of your rope!
4. Learn how the machine works, make your own logic diagrams, then add comments and symbols. Whether you can do this depends on how complex the machine and how great your ability.
5. In the future, do not buy a machine without getting everything you need to maintain it, including a complete copy of the program.

thank you

Lancie1 said:

In the future, do not buy a machine without getting everything you need to maintain it, including a complete copy of the program.

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Lancie,

some of the machines where I work did not come with a copy of the program. I've asked the powers that be for them, but was told that they never came with any. The all utilize Moeller PLC's, and i've never seen any software for them either.
Thankfully, they've all ran good for a long time and I assume if they go out, we'll just order another one with the program already in it.
So my question is this, how common is it to buy new equipment without a copy of the program in the plc?

So my question is this, how common is it to buy new equipment without a copy of the program in the plc?

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Unfortunately, in many cases the persons responsible for deciding which machine to buy do not understand PLCs enough to know that they are buying only half a loaf of bread. When they need the other half they often find that the price has tripled, or the program is obsolete and no longer available in that format, or the guy who maintained it left and took it with him, or the company was bought by their competitor (who did not keep the old programs).

I think it is like buying a car and not getting a spare tire. Perhaps a more exact analogy would be: buying a car with special wheel locks, so when you have a flat you have to go back to the vendor and beg for a wheel lock key.

I never recommend purchasing any machine unless I get the WHOLE THING, including everything needed to maintain, modify, upgrade, and rebuild it. The only time you can negotiate this item is before the purchase. Afterwards it is too late, so prepare for a severe money drain in the not-too-distant future.

Back in the old days, when machine programs were controlled by relays, step relays, and drum sequencers no company could have sold a machine without those parts (including a complete ladder diagram showing how it all worked - the program). How come many of them are now allowed to sell a machine without providing a copy of the PLC program?

Lancie1 said:

Unfortunately, in many cases the persons responsible for deciding which machine to buy do not understand PLCs enough to know that they are buying only half a loaf of bread.

Click to expand...

I hear you. We had just that sort of thing happen several months ago. The purchaser of the machine on our end had the option of two PLCs - he picked the cheap one. It was known all along that we would have to modify it to integrate it into our system. Our automation group never got wind of it until after the machine was uncrated and moved into place. Surprise! We didn't have the software or the comm adaptor. The software was a lot more than the expensive PLC (for which we already had software) would have been.