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Interfaces of the ACU
98-166784-A
Chapter 4: Interfaces
4-3
4444
Interf
aces
NMEA 0183
The NMEA 0183 connection supports EN 61162-1 (baud rate 4800, format 8N1) and EN
61162-2 (baud rate 38400, format 8N1). The ACU detects the baud rate automatically, you
cannot configure this interface.
Supported NMEA sentences, in order of priority:
• HEHDT (North seeking Gyro compass)
• GPHDT (GPS compass)
• HNHDT (Non-North seeking gyro compass)
• IIHDT (Integrated Instrument)
• HCHDT (Magnetic compass)
Recommended NMEA 0183 cable:
Two-wire constructed with one enclosed shield
Network signal pair:
• Size: No. 24 AWG (0.24 sq. mm) or heavier
• Characteristic impedance: 95 - 140 Ohm
• Propagation delay: 5 nanoseconds per meter, maximum
• 15 Twists (minimum) per meter
4.1.6
RS-232 and RS-422 connectors
The ACU has an RS-232 and RS-422 connector. The connectors are not used in normal
operation.
1. (Hardware prepared for NMEA 2000, for future use). NMEA 2000 power: 9-16 VDC. NMEA 2000 LEN
(Load Equivalency Number): 2 (100mA)
Note
Any HDT sentence is supported as long as it complies with the following header
format: "$xxHDT", where xx can be two characters e.g. IN for $INHDT
Outline (on the ACU)
Pin
Pin function
1
Not connected
2
RXD
3
TXD
4
DTR
5
Ground
6
DSR
7
RTS
8
CTS
9
Receive Signal Strength Indicator
Table 4-5: RS-232 connector, male, outline and pin assignment, ACU
1
5
6
9