I understand what's being asked: "Hey, the SLC-5/05 has an Ethernet port, and some manufacturers are selling Ethernet-based I/O modules now. Can I use that I/O, dispense with the special I/O scanner cards, and steal all my physical media from the old server closet ? "
The short answer is no.
The long answer is also no, but it's because the SLC is a nice mature control platform with enough sense to not go running off after the latest network media or protocol fad. It's nights like this I'd like to track down the jerk who wrote that puff piece in Managing Automation last year about Calloway Golf's choice of Ethernet I/O: "...I won't buy anything that won't let me assign an IP address....". That magazine would be worth more if they printed it on absorbent paper so I could wipe my butt with it. banghead
Fear not, K.C., my rant time is over and here's the straight scoop:
The SLC only uses it's 10BaseT Ethernet port for unscheduled messaging to peer controllers, operator interface terminals, and software interfaces for programming and monitoring. It implements the Rockwell proprietary "Client-Server Protocol" (PLC-5E have used this for years) as well as part of the Information portion of Rockwell's "Control and Information Protocol" (CIP).
It does not implement the Control part of CIP. Although you can send MSG instructions out the Ethernet port from ladder logic, they're exclusively for peer-to-peer communications between controllers.
Several of the ControlLogix family of controllers do implement this functionality, and Rockwell is building EtherNet/IP protocol adapters for most of their modular I/O products (FLEX, Point, Compact, etc).
The SLC just doesn't have the processor horsepower in it's communication daughterboard to work as an Ethernet I/O scanner. I like the SLC-5/05 and work with it all the time, but the architecture isn't built for a high-speed communication interface on the front port, and and the product line is old enough that Rockwell is going to put their development efforts into the ControlLogix and let the SLC do what it does well.