The network comprises a master unit 10 and a plurality of slave units 20 to 25. The master unit is arranged to send messages to, and receive messages from each slave unit. The master unit issues a log-on request message which is received by the slave units, but only the slave units which have not communicated with the master unit before (ie. new slave units) respond to the message. In this way the master unit recognises new slave units connected to the network, enabling the master unit to communicate with them. The network may be used to remotely read electricity meters and automatically recognises when a new meter is connected to the network.
