Another simple question

Hi everybody.
Sorry, I have a new simple question: what are the purposes and advantages of communicating betwen Plc´s in a network.

The biggest advantages are the availability of data between all of the PLC's/devices on the network and the ability to access devices on the network from one or multiple locations.

Along with the availability of shared data is a reduction in field wiring. Philosophically, I still want to keep my critical signals hardwired. (trips and certain permissives)

Sometimes it's just because of the system need.

If you need to interconnect the machines, then it can be helpful if they can communicate with each other.

But then, you can pull the plc's all out and put in one big PLC or a ControLogix system.

I have had several hundred PLC's in one area of a tire plant, and none communicated with any others. There was no need for them to. And they were all happy, except maybe the Sharks and DL100's.

I did have two Opto22's in the "pit" that monitored temps and pressures in tire curing presses (waffle irons for tires) that was tied into the main frame, and it they didn't like that at all.

Ya just can't please EVERY plc.

regards.....casey

Hi folks....This post caught my eye because we just got a proposal from one of our vendors on using communications between the PLCs in our dye machines and a PLC or PLCs recieving outputs from flow meters. In other words 1 flow meter would service a group of machines instead of individual flow meters for each machine{as it is done now}. An earlier "idea" would have required indvidual coduit runs from the output of the flow meter to each machine. By using the data hiway and MSG functions {SLC500 and PLC5s on our network}we save money by not having to hire contractors to run all that pipe that we don't need to buy to begin with. I hope this example answers your question and I hope my company goes with this proposal cause it sounds like a neat learning project.Ya'll keep your fingers and toes crossed for me.

Later....Todd