A communication system includes two or more command devices, each being capable of transmitting command signals over a communication interface; two or more response devices, each being capable of receiving such command signals over the communication interface and being capable of performing a non-communication function in response to such a command signal; at least one of the devices being remotely configurable so as to: if that device is a command device direct its command signals to a specific one of the response devices to the exclusion of one or more other of the response devices; or if that device is a response device accept signals from a specific one of the command devices to the exclusion of one or more other of the command devices.