The RINA approved engine telegraph has the characteristic to use only 3 wires for both power supply and communication line among devices, thus simplifying installation and maintenance. Dimension are standard 144×144 mm. It is possible to connect together up to 5 units: bridge, two wings, ECR (engine control room) and engine room. The bridge unit transmits all info for a VDR system, with an RS232 NMEA standard protocol. Furthermore each unit has an isolated normally closed contact which can be connected to an alarm or monitoring system, in order to give an immediate alert in case of malfunction.