Auto rs422 switch

Hello Everyone.

First let me say that I am not an engineer of any kind. I know a little about electronics. I have a project I would like to build. I have 4 different types of controllers that use RS422. All 4 controllers have their own place and purpose. They all control PTZ security cameras. What I am looking for or want to build is a device that will auto switch from one controller to another when a signal come in to it. I can't use a manual switch because no one will not be by it to make the switch. I have seen switches that have 1 device in and multi devices out but not the other way around. Is this even feasible? If feasible, would it be difficult to design and build using discrete components or AVR micro-controller (single sided board).

Thank you in advance.

Dennis

nemocam.com