setting up rio com link

hello,

I am having some issues with getting my 1747-SN to communicate with some Flex IO modules via RIO.. I am not familiar with this.. and have been reading about M0&M1 files as well as G files.. I have set the G file length to 3, M0&M1 to 3300, and my logical Rack 0, Group 0 is set for a full rack. (I have 4, 1794-IB16's and 2, 1794-OB16's) Do I require a move or copy instruction of some sort for these values to be sent to my output modules and read from the inputs? however, my current processor type does not support the BTW or BTR instruction types... my processor is a 1747-L542B (SLC5/04 CPU - 32K Mem. OS401)

I have attached a copy of my program.. any help is greatly appreciated.

Thank you,

Jason Lash

Try changing the Rack Size in the 1747-SN Scanlist to "3/4 Rack".

The 1794-ASB adapter sets its I/O "rack size" based on the modules it detects at power-up. 6 total discrete modules is a "3/4 Rack".

The FLEX platform doesn't let you define a larger or smaller Rack Size than the I/O modules that are actually present.

how does one know, whether it is a 3/4 or full rack? i wasn't able to find any documentation on the sizing.. just saw references to said sizes..

Also, Ken, are the move, copy, btr,btw instructions not required for this application?

just looking for the reason that i have no coms between the racks..

The old Allen-Bradley Universal Remote I/O addressing scheme is so old (1978 !) and varied that most product literature since the 1990s has been reference style, rather than "layout and introduction" style. You really have to go back to the PLC-2 and PLC-5 user manuals for the basics.

It can sometimes be tricky and subtle, but the most common mode is "16 point single-slot addressing", where a "Rack" is eight modules. That's what you should use.

If you have an odd number of modules, you round up to the next largest 1/4 fraction.

There are quite a lot of 1747-SN and RIO configuration threads here on the Forum, but we can certainly do another. We know your 1747-SN physical configuration and 1794-ASB physical layout, so the next steps are to post the DIP switch settings on the 1794-ASB (include the exact part number because the Series letter is important) and troubleshoot the wiring and indicator lights.

Also: these discrete I/O modules do not require any block transfers or extra logic to get their data into the I/O image of the 1747-SN.

Since you have said that you're unfamiliar, I think it's worthwhile to also mention that you need to make sure that all of your devices are operating at the same baud rate.

I assume that's a typo and you have a 1794-ASB Series E.

RIO is actually extremely forgiving about wiring, so go ahead with that wire for now. Do install a 150 ohm resistor across the blue and white wires at each end.

"Conductor 1" is the top terminal on the 1747-SN, and the left terminal on the 1794-ASB. Make sure your wiring is 1-1, Shld-Shld, 2-2.

There should be some indicator lights on both the 1747-SN scanner and the 1794-ASB adapter. Observe and describe those.

The RIO protocol goes way back to the PLC-2 controllers and formed the backbone of A-B's I/O handling for a very long time. FLEX was added to the RIO product family in 1994 or so.