Starters & Valves plugged into I/O


Thread Starter

David R White

I work for a Material Handling SI. As you can imagine, our systems use drives, motor starters, pneumatics, and I/O...a lot of I/O, all networked together. My boss asked me to look at how we can cost-reduce our systems, but of course keep all the functionality. Right now we're spending a lot of money on products that connect right to DeviceNet. For larger conveyor sections, we have to install more DeviceNets because we're running out of node addresses. I/O isn't the problem, it's the valves & motor starters that are chewing up our node addresses. I've heard about starters & valves that plug right into machine-mount I/O. The idea sounds like it could help me save a network connection and maybe keep from having to install more networks. But, we really need the constant feedback on the health of all the components. Does anyone know who's making these kind of products? Can this save me money and still give me the starter & valve diagnostics that DeviceNet gives me?
I don't know if you've looked into it yet, but Allen_Bradley makes a line called FlexIO that communicates over DeviceNet (and ControlNet, too, I think). It is designed to be machine-mounted IO that is controlled by a remote processor via your chosen network. They offer analog and digital IO, and even have an explosion-proof flavor.(Flex Ex) Unless I've missed the point of your message, it sounds like this might be worth looking into.
There is a company called Interlink BT that specializes in connectorized I/O and they make a lot of products for DeviceNet. You can hook up several devices up to one I/O block and only take up one Node.
I too have looked into machine-mounted I/O for the very reasons you've stated... recently had the realization that (beleive it or not) Profibus I/O is really cheap and might not eat up your nodes as you related. Granted, 16 (10-I, 6-O) points would be a minimum starting point per node, but you could eat that up pretty quick if you're doing 2-4 here or there. From your msg. I'd gather you're looking at both analog and discrete I/O. I know AB will eat up 2 words per channel for analog and one word per 16 point card for discrete. A AB RIO scanner supports 32 words per unit (in the master) along a DH+ link. AB allocates 32 In and 32 Out so if you're smart you place the cards in a RIO rack side-by-side and get your money's worth. DH+ is slow, so don't count on it for precise motion control, etc. DeviceNet may be the way to continue, but look at your field devices. It may be reasonable to use a DeviceNet conventional slave at various machine locations and go from there. I've read about (but never used)'s Terminator I/O. Really cheap and very interesting, and if you're already using DeviceNet it's worth a look. I've got a project now that requres remote start-stop-current monitoring and reset of older AB MCC's that I'm looking seriously at using this approach. My only problem is the cost of getting AB to talk DeviceNet. Any suggestions along this line would also be appreciated. I could go RIO and ASB but man it's expensive!!! Good luck and let me know... John Kelley [email protected]