tousey

G'day, As TWControls mentioned, watch your distances with DeviceNet, go to the Rockwell site and there should be a manual to help with the planning. I would probably go Devicenet, maybe because I am more comfortable with it, but you have a good variety of devices to put on it. Use care if you start looking at the flat trunkline cable, 2 off the 3 installs have given headaches. Not as noise immune as the sales people tell you. But with the 30+ other cable installations, I have only one that 'plays up', and that is because it is a badly installed job, not by me.. I would check out AB's PointIO and Wago's IO system, which allow for a variety of low IO counts. The other bonus is you could look at using DeviceLogix in the distributed IO, just simple logic in the IO which can be used if the processor 'crashed'. Also look into the E3Plus overloads, great item, the also have 4 inputs and 2 outputs available, as well as being an intelligent overload. Cheers, Trevor.

G'day Chavak, Global Status words are a great way to pass a small amount a data around your DH+ network, and it is a shame that Rockwell didn't implement this on ControlLogix DHRio modules. Basically, there is an Int (16bits) from each SLC5/PLC5 node available on the network. In the SLC you need to enable the transmit and recieve control bits (set to 1) and then the data you want to send out is put in S:99. This is then read in the S:100 - S:163. If you are transmitting data from the SLC at Node 4, then the data is read in S:104 in any of the SLC's connected to the network. And if it is Node 10 (octal) it would be in S:108, the octal-decimal node numbering can be misleading. The good thing over using MSG's is that it just keeps on working, now lock-ups or timeouts. The only drawback is it is only one word (16 bits). Cheers, Trevor Ousey