And we're talking $100 here, not $10K. I'd never even consider a Click unless it were for a product line where I expected to ship 1000 units and all you had to do per unit was load it, OR just using it as passive Modbus RTU or TCP I/O.
That's exactly the plan. We intend to use a low end PLC to take the various machine signals to generate 3 or 4 "states" that our SCADA software could use. Use them as a 'black box' per say to let our Maintenance Server know what is going on.
For example, one our welders needs to be in Automatic Mode, Pumps Running, Machine Enabled and the Speed Control Lever not at Zero to be considered producing. But the loop comes from the fact you can have any one of those conditions met at any time. We plan to use the PLC to take the input signals and figure out if the machine is running, and by counting shaft RPM, at what speed.
The other design rule we are using for this project is that the PLC is read only for production machines. The supervisor couldn't stop the machine from his office or anything like that.
The thought came from our boss wanting status lights in each of the main offices that would give machine status. Weidmeuller came in with a $2500 per machine solution. That would give us just lights... I said why not just use SCADA software running on our server and tie in a black box on each machine to act as semi passive IO. Each machine has an ethernet port near the operator's console to run our ERM clients. Just tie into that connection. Anyone in the plant could see what was running and what speeds. Then we could add the ability to page maintenance and ETC...
Right now, I'm in the costing phase, looking at what all the options are. I've looked at the ProtosX, which wouldn't allow me to preprocess the signals, the click which is limited on what it can do, and the do-more.