The Integrity Instruments RCE-1 allows the user to monitor contact status at
one location, and send these signals to a remote location. There are two units
supplied, a master unit and a slave unit. The system is bi-directional allowing
contact status at the remote location to be sent back to the other end. Up to 8
inputs at each end can be sent as outputs to the other end. The uniqueness is
that this is done over a single twisted pair of wires.