Furuno FA Manual page 272

APPENDIX
Serial interface – output ports
ARPA for ECDIS
Dual differrential
drivers and receivers
SN751178NS
Logical High: A-B> +0.2V
Logical Low: A-B< -0.2V
Serial interface – input/output ports
Transmission rate is selectable from 4800 bps and 28.4 kbps.
Input port (RD-A, B)
Isolated RS485 Transceiver
LTC1535
Logical High: A-B> +0.2V
Logical Low: A-B< -0.2V
Output port (TD-A, B)
Isolated RS485 Transceiver
LTC1535
Logical High: A-B> +4.0V
Logical Low: A-B> -4.0V
AP-28
RD-A
RD-B
RD-A
RD-B
GND
TD-A
TD-B
GND