A control system, method and computer program are provided for communicating control information in a control system. The control system includes a master controller and a plurality of devices. Each of the plurality of devices have a number of channels. Each channel has an identifying number and a plurality of channel states. The method includes at least initially directing one or more messages sent to and from each device to the master controller, sending a first type of control message from the master controller to respective devices, and sending a second type of control message and a third type of control message from the master controller to respective devices. A control message of the first type directs the respective device to place one of its channels in a specified channel state. A control message of the second type directs the respective device to set the level of a specified parameter to a certain value, and a control message of the third type comprises a character string of variable length.