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GENERAL
NS 4000 ECDIS MFD system is equipped with NMEA ports, which are completely
corresponding to IEC 61162-1,2 Standard requirements.
The following terms are used in this Annex:
•
Talker – NMEA port Output, which transmits data to other devices;
•
Listener – NMEA port Input, which receives data from another device.
All signal line A connections are connected in parallel with all device A connections,
and all signal line B connections are connected in parallel with all device
B connections. The shields of all Listener cables should be connected to the talker
chassis only and should not be connected at each listener.
The idle, marking, logical 1, OFF or stop bit states are defined by a negative voltage
on line A with respect to line B.
The active, spacing, logical 0, ON or start bit states are defined by a positive voltage
on line A with respect to line B.
To meet the demand of high reliability in industrial environment and to prevent
the boards from damage caused by lighting or high potential voltage, an optical
isolation (2 kV DC) is implemented in the Listener’s receive circuit.
The Listener’s receive circuit is designed for the operation with a minimum
differential input voltage of 2,0 V and shall not take more than 2,0 mA from
the line at that voltage.
The drawing below shows the connection corresponding to the Talker/Listener Interface.
Fig. 74. COM-Ports interface diagram
Fig. 75. Talker/Listener interface diagram
Annex D. COM-Ports Interfaces
General
307
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