PLC 5 (1785-L20B Processor key switch)

iraiam

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Hi, I have never set up a PLC 5 system from scratch before, I bought a 16 slot rack full of goodies, for a home automation project, but guess what. The processor has no key!:mad: It's in remote so I'm not in dire need yet.

Are all these processors keyed the same? It is a 1785-L20B C processor if that matters.

Does anyone know where I can get a key for it?

Thanks much
 
I have never tested it, but I am pretty sure they are all the same. That is my experience with all the PLCs I have worked on. You might still be able to get them from Allen Bradley. I don't have one here to see if it has any number on it.

Stu....
 
Rexel probably will give you a key. All A-B PLC-5 processors use the same key. Possibly with the exception of the secured processors. The ones that ended in a "6" had additional security options but I think they still used the same key.

OG
 
It's called an "A126" key. Every PLC-5 controller used the same one, and every PLC specialist or manager has a drawer full. Trade them an opportunity to talk to you about other automation products or services your company might need now or in the future.
 
Hi Gents...
I am firly new at PLC's I had a Q's, I have a 1785-L20B / C
that my brother gave to me along with a box of other goodies, do I need to buy software to wipe out the memory or does it store any history of prior code, somebody mentioned that it works a server processor. Any thoughts?
Thank You,
 
MarkJ30 said:
Hi Gents...
I am firly new at PLC's I had a Q's, I have a 1785-L20B / C
that my brother gave to me along with a box of other goodies, do I need to buy software to wipe out the memory or does it store any history of prior code, somebody mentioned that it works a server processor. Any thoughts?
Thank You,
Click to expand...

Just power down and pull the battery out, the memory is gone. It will be in its default state.
 
Last edited:
Hey Mark, you might get more visibility to your question if you post a new question instead of adding onto a two year old thread.

But nonetheless, here you are and welcome to the site.

The PLC-5 does need software to program it. And....it's really, really expensive software. Several thousand expensive. In the box of goodies, is there any software? You are looking for something called RSLogix although you might also see these older products:
  • WinLogic 5
  • 6200
  • Icom Ladder Logistics
Do you see anything like this?

OG
 
An Allen Bradley PLC5 1785-L20B / C programmable logic controller is indeed an acutal controller. It says so right in the name. You can use it to control many on/off outputs, and also analog-range (varying voltage or current) outputs.

Many PLC5's are also used to transfer operational information from a process to a user operator panel (HMI Human-Machine Interface).
 
Last edited:
Hi iraiam

You said the plc is in romete but this is fine to get started with till you get a key as you can online edit, download and run the program.
I have a plc 5 key on my work keys and this has worked on ever plc 5 processor I have come across

Donnchadh
 

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