85
COM1 Connector
This nine-pin connector actually consists of two connectors (RS-232 and RS-485) at-
tached to one logical port. Only one connector can be used at a time.
RS-232 Connector
The lower nine-pin connector provides the RS-232 protocol.
Pin
Signal
1
DCD1
2
RXD1
3
TXD1
4
DTR1
5
GND
6
DSR1
7
RTS1
8
CTS1
9
RI1
RS-485 Connection
The upper nine-pin connector provides the RS-485 protocol.
Pin
Signal
1
TXD-
2
TXD+
3
TXD TERM -
4
TXD TERM +
5
GND
6
RXD-
7
RXD+
8
RXD TERM +
9
RXD TERM -
Note
For TXD termination, connect a 150
Ω
, ½-watt resistor from pin 3 to pin
4, with pin 1 connected to pin 3 and pin 2 connected to pin 4.
For RXD termination, connect a 150
Ω
, ½-watt resistor from pin 8 to pin
9 with pin 6 connected to pin 9 and pin 7 connected to pin 8.