View Full Version : Remote I/O

October 18th, 2007, 10:41 AM
Im am designing a system containing a compactlogix controller with controlnet communication. I have some 24V I/O (8 inputs and 8 outputs) 1000 meters (3280 feet) away from the controller. I am looking for some recommendations on how to communicate with the I/O. The communication doesnt have to be fast, the I/O is mostly pushbuttons and lights. Should I go with controlnet? I might have to get a repeater (control net on coax is only good for 1000 meters). Should I go with remote I/O (I would need to purchase a card )? I am also not sure about the I/O module choice either. Point I/O or Flex I/O? any help is appreciated. thanks

October 18th, 2007, 11:30 AM
As you have already ControlNet onboard the CompactLogix then that is the natural choice.
You can extend the ControlNet with fiber repeaters. Here is a document explaining it:

October 18th, 2007, 11:34 AM
Well is there a pupose you are using a Controlnet processor? If you use a processor with Ethernet/IP you could run fiber out to your remote station. There is no AB "Remote I/O" for compactlogix. Running coax that far will be more expensive than a fiber run i would imagine.

October 18th, 2007, 09:26 PM
For I/O, and since you already have controlnet, definitely cast my vote for that over ethernet.

Use ethernet for HMI, programming terminal, and any peer to peer stuff so you don't have to buy a PC card for controlnet.

Get the ControlNet Media planning guide from ab.com too...There will be more planning and work in the media installation versus the ole blue hose RIO, but it's a super fast, reilable network in my limited experience. Easy to diagnose and keep downtime to a minimum.

The only failures I have seen were both acoompanied by flashing red LEDs on the faulty segment pointing to a failure of a passive tap, and the other was a "failed" repeater (not a fiber optic one).

It is very simple to dial the node number on any c-net network device with a screwdriver and plug and play...much more maintenance tech friendly IMHO. Both times the on-shift tech got it going without having to call in engineering support.

1 more vote for C-Net

EDIT: If you spring for the PC card for controlnet, you can plug into your remote rack and have ethernet speed to program your CPU 3280 feet away. This was very handy on our machines, to be able to park my PC right by the I/O I was working on and debug, and fine tune speed controls, etc...