How to use AB remote I/O from Linux

Hello,
I'm interested in using Allen Bradley Remote I/O, but would like to do it without a PLC. I would like to control it from a Linux embedded device.
We were told to look at the ODVA - EtherNet/IP/CIP material for doing this.

It would seem to me I'm reinventing the wheel and wondered if there is a faster way to do this.

I'm realitively new to the PLC world, so it's been tough trying to come up with the right answers for this.

Any help would be appreciated.
Thanks
Pat.

Anytime this is discussed, the general conclusion is that in the amount of time you'll spend coming up with some kind of a custom solution, you'll be both money and time ahead to start out with an AB PLC in the first place...

AB holds on to thier protocol information like its some sort of national treasure...unless you are an "encompass partner"...more or less a conspirator. Anyhow, AutomationDirect terminator I/O is great for what you're talking about with Linux control.

Since AB RIO is both proprietary and more or less obsolete, to invest a lot of effort would be a bit of a waste.
Consider Profibus, ProfiNet, DeviceNet or Ethernet/IP. There are already some Linux solutions and/or user groups for these. And they are a lot more future-proof than AB RIO. If in doubt go for one of the ethernet based protocols.

First, let's take a step back and distinguish between Allen-Bradley networked I/O platforms and the Allen-Bradley Universal Remote I/O Protocol, aka "RIO".

The Universal Remote I/O protocol dates from the late 70's. It runs on a blue-jacketed Belden twinaxial cable that gives it the nickname "blue hose". It's compatible with A-B programmable controllers for generations; the PLC-2, PLC-3, PLC-5, SLC-500, and ControlLogix all have scanner ports and modules for this protocol, and almost every A-B I/O platform, drive, motion controller, and operator interface terminal has a RIO option.

RIO is very proprietary; there are only a handful of third parties who have ever been granted a license. This was done as much for stability and accountability as for market protection; A-B can guarantee the functionality and reliability of RIO devices to a much higher degree than any open network.

Allen-Bradley made the leap of faith to nonproprietary protocols in 1995 with DeviceNet, then with ControlNet and most recently with EtherNet/IP. While they disappoint the free-as-in-beer zealots, the protocols are maintained, licensed, and tested by the Open Device Vendor's Association (ODVA).

All the modern Allen-Bradley modular I/O devices support one or more of these protocols. Bulletin 1734/1738 POINT/ArmorPOINT, the venerable 1794 FLEX platform, and the 1756 ControlLogix platform are the most popular EtherNet/IP platforms. The Input, Output, and Configuration assemblies are generally described by Electronic Data Sheet files, though some of the functionality of the more complex devices in 1756 are encoded in the RSLogix 5000 editor and not published.

If you're looking for a Linux stack for an Adapter or Scanner on EtherNet/IP, I wholeheartedly recommend Pyramid Solutions (www.pyrasol.com). Pyramid are expert enough that RA licenses some of their implementations for use inside A-B labeled products.