The application relates to modular electronic apparatus (1) for distribution of RF communication signals. The apparatus comprises a chassis (2) arranged to removably receive plural modules (3), at least some of which are arranged to receive and process RF communication signals. A communication path (17) is provided for modules to communicate with each other and/or with the chassis. Plural modules received in the chassis. When a module is received in the chassis, it is arranged to broadcast a message over the communication path indicating its presence in the chassis and its type. At least one other module is arranged to adapt its behaviour in response to the message.