A network communication system (2) for two-way communication comprises: —at least one group of network devices (11); —at least one command device (20) capable of issuing at least one command signal (SC); 5—coordinating means (40) provided with a network definition memory (41) and with a device status memory (42). A network device, in response to receiving a command signal (SC), sends an acknowledgement signal (SA) to the command device. The coordinating means, in response to receiving a command signal for a 10 network device, watches for the corresponding acknowledgement signal from that network device and, in case of that network device failing to timely send the acknowledgement signal, amends in said device status memory (42) the status information (M(i)) relating to said network device. The coordinating means automatically removes a potentially defective 15 network device from the network definition memory (41) on entry of a network amendment mode.