Janzen Electronics.  http://individual.utoronto.ca/janzen/electronics

Radio Transmitting Computer Interface

This series of products, currently in development, use a new method of electronic radio communications to receive and send commands. The system is meant to be controlled by JE's VOCL computer program. Up to 254 local modules can be controlled by a single server module which can be connected to a computer. The method of communication used is a "Don't speak unless you're spoken to" protocol. Each module can handle several digital inputs and several switched outputs as well as an audio signal. All of the data can either be stored temporarily in the server module or loaded on and off the computer.

Modules can also be connected by cable, which centralizes the power sources instead of each remote module being battery powered.