1791 Remote IO - PLC5 help

[swapped]

Hi Everyone

Have a really old line with a PLC5/30 and a lot of remote IO.

Had a 1791-OA32 (32 point output module) module fail and all I have in stock is a 1791-16AC (16in/16out).
I'm not a PLC5 or remote IO guy. I was thinking it would be simple to add the new module but I'm finding that the PLC is setup for complimentary IO and I saw a note in one of the manuals where it says I can't add the input/output module as complimentary IO.

How can I add this thing to the network and make it functional?

Thanks

 

[James Mcquade]

swapped,

you can't add the module to the remote I/o when it is set up as complementary io.

if the main rack is available, you might be able to insert it there.

google the part number and you will find lots of places to get the module.

regards,
james

 

[swapped]

Thanks for the response. I ended up getting another 1791-0A32 and doing a direct swap.

Thanks again!

 

[Ken Roach]

You did the right thing, of course.

Block I/O was not a long-lived product, and Complimentary I/O is an unusual mechanism for A-B RIO networks, but you happen to have both.

For future readers:

Complementary I/O is a way to conserve addressing memory in old Allen-Bradley controller systems that used the Universal Remote I/O protocol (RIO).

Ordinary I/O chassis have both Input and Output memory assigned to them, so you can install both Input and Output modules in the chassis.

The way Complementary I/O was implemented was that you'd have a whole chassis that only had Input modules. You could then install a whole chassis that only had Output modules, and they could share the same Rack Number.

Rack Numbers are valuable because the old logic controllers didn't have much I/O memory.

Because the combination modules has both Input and Output memory, it can't be used in any Complementary application, even when placed opposite another identical module.