User's Guide

9
SERIAL OUTPUT
The ICS NAV5plus has an EIA RS422A-compatible serial output which can
be used to connect the ICS NAV5plus to other equipment such as an
integrated bridge system or a PC running charting software.
The serial output operates all the time that the ICS NAV5plus is switched on
– there is no ON/OFF control for the serial output.
All correctly received NAVTEX messages from the 518 kHz receiver are
sent to the serial output. The station and message category settings for
printing within the ICS NAV5plus are ignored.
It is anticipated that the external equipment (e.g. a PC running charting
software) will have its own method of selecting stations and message
categories and as such ALL NAVTEX messages received by the ICS
NAV5plus will be output.
Note: Only messages from the 518 kHz receiver channel will be present on
the RS422 serial output.
Connecting to the Serial Output
Main Connector
Pin Function
3 EIA-RS-422-A Output (TxA)
4 EIA-RS-422-A Output (TxB)
The RS422 output is ‘simplex’ which means that multiple receivers can be
connected to the ICS NAV5plus but the ICS NAV5plus is the only
transmitter.
The RS422 standard for connecting equipments specify that, for a short
cable with only one receiver, the cable may be unterminated. For longer
cables (20 metres or more) or installations with multiple receivers, a
termination resistor should be fitted at the far end of the cable run from the
ICS NAV5plus. The resistor value should be the ‘characteristic impedance’
of the cable, which typically is 100 to 120ohms. A ¼ W resistor is sufficient.
The cable used should be twisted pair 7/0.2 mm or similar.