We have a machine which has a GP2600 Proface to AB SLC500 processor. We have a ton of this type hookups, but on this machine they are asking to have a duplicate Proface on the back of the machine. Hooked up in parallel with a key switch or some device to give control from one to the other. This is so the operator can start the machine from either front or back. (large machine) proface talks to the processor through an rs232 hookup. Anyone ever dealt with this?