Two Independent control rooms to share a common circuit

Here one for comments/suggestions: An independent plant (control room) ten-miles away will convey its material then discharge onto a conveyor of another plant(control room). What would be the best method to share control of this conveyor via the HMI/PLCs? Both control rooms use Wonderware Intouch 7.1 as the topology and both circuits PLC are Modicon 984. Thought is to pass a token via the HMI's giving control of the final/end conveyor (somehow

Why would the discharge plant control the receiving plant's conveyor?

The first thought that came to mind was the Sorcerers Apprentice.

There you are at the end and you are drowning in material - would it not be nice to turn the thing off?

I think controls at each end of a conveyer would be a good idea - at least an e stop.

I am not sure what to say on a 10 mile conveyer and have difficulty imagining ten miles of control circuit. I would think there would be E stops at intervals of conveyer(s) - can you really have a single 10 mile belt type conveyer?

Dan Bentler

There are also four HMI across the length of the belt; emergency pull cords, belt drift switches on all belts. Emergency stop on the overland conveyor I understand will be near a minute. The final section of belt or where the overland conveyor discharges onto will be hard wired to stop the overland if it were to stop/trip. Perhaps thats all that is needed...

Is that a single 10 miles long belt conveyor ? Gosh.

I would start to investigate single mode fiber, look into what Modicon supports. Probably Modbus TCP will do.

The problem as I see it is the wirestops. Are there safety relays that can drive cables that are 10 miles long ? I used to get into problems when the combined cable length reached 200-300 meters. The voltage drop would cause the relays to trip. I think that todays safety relays are less sensitive to this problem (the safety circuits draw less current), but 10 miles is a long distance.