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Testing a PLC

Posted by pharkus (My Page) on
Thu, Dec 31, 09 at 23:26

I know this is slightly beyond the scope of this forum but it's not a far stretch to imagine that someone here has experience with these things.

I just acquired an Allen Bradley SLC-150 Processor Unit. I intend to resell the darn thing, but would like to be able to give a potential buyer some idea of its functionality.

I went ahead and wired up an AC cord to "115/230 VAC" and "115V NEUT" and plugged it in. "DC POWER" and "CPU FAULT" light up. The latter flashes/flickers a couple times so something in there is doing something, but I have no idea if it's doing what it should be.

This one does not have the optional battery, and has definitely been unplugged for more than a couple weeks. It definitely has no program in RAM, but it does have an EEPROM. Of course, I have no idea what program is in the EEPROM. My brief google searches have indicated that there has to be a comment added in the program in order to allow it to be autoloaded from the eeprom, and I don't know if that comment is in there.

Will a complete lack of a program cause the "CPU FAULT" LED to be lit? What further do I need to do in order to get this thing to pretend to do something functional? Downloading something and fabricating a cable to attach to a PC is not beyond my ability if that's what it'll take...

Follow-Up Postings:

RE: Testing a PLC

Since you seem to have successfully plugged it in, I think posting your questions on the Computer Help would get better results.

RE: Testing a PLC

I would expect the 'computer help' forum to be related to PCs and Macs - "computers" in the normal user sense.

In a factory or industrial environment where this thing would be likely to be used, when one fails, who gets called? The electricians do - not the IT guys.

A person with PLC experience is more likely to be found in an electrical forum than a computer help one.

RE: Testing a PLC

pharkus - I've been an industrial electrician for 22 years, and have been programmimg PLCs for about 12. Generally when you see a cpu fault like that, it's because something previously connected to it has been removed - like on a network or similar. Here's a link that will tell you everything. Look at page 160.


Here is a link that might be useful: SLC hardware manual

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