User's Manual Part 2
25
12V or 24 V DC power connection
A connection must be made to a 12 or 24 V DC supply via a circuit breaker capable
of supplying at least 2 amps. Connection should be to the ship’s radio battery and
be in accordance with GMDSS requirements.
• Connections should be made using the 2 m power cable provided
• Use cable ties to restrain the wiring, and so prevent it becoming weakened
by vibration. The connecting cables should be restrained by securing them
to the rear of the NAV-7 bracket, or to adjacent metalwork
• The screen of the cable should be connected to ship’s earth if possible.
The screen of the cable should not be connected to ship’s battery –ve
Safety Warning
The NAV-7 has been designed and manufactured to be completely safe
when used in accordance with the instructions given in this manual. To
ensure that the complete installation is safe, it is essential that a fuse or
circuit breaker is installed in the power supply cable as described in the
Installation section of this manual.
Isolation between the power supply connections and any other connection to the
NAV-7 is 1 kV minimum.
The DC power source should comply with IMO guidelines for the class of vessel
concerned. National authorities and classification societies may have their own
power supply requirements; these should also be considered.
Signal cable connections
As shown in the table above, the NAV-7 may be connected to different types of
peripheral units including IBS & INS serial ports and printers.
The signal connections are all connected via a serial RS422 type interface; data
rates are selectable at 4800, 38400 or 115200 baud.
In some cases, particularly in retrofit installations, it may not be possible to connect
the NAV-7 directly to the required source/destination for serial data, because some
equipment does not provide the IEC 61162-2 (NMEA) sentences required by the
NAV-7 unit. In such cases a protocol converter is required between the sensor and
the NAV-7. Converters are available from different manufacturers, either as direct
protocol converters or frequently as repeater instruments for the sensor.