Table 4–3 COM3 and COM4 connector pin-outs (J17 connector)
COM3 COM4
Pin# RS–232
signal
Pin# RS–232
signal
1
2
3
4
5
6
7
8
9
10
nc
nc
RxD
RTS
TxD
CTS
nc
nc
GND
nc
11
12
13
14
15
16
17
18
19
20
nc
nc
RxD
RTS
TxD
CTS
nc
nc
GND
nc
Table 4–4
COM3 and COM4 RS–422/485 connector pin-outs
J15 COM3
connector
J14 COM4
connector
Pin #
Signal
Pin #
Signal
1 TXD+
1 TXD+
2 TXD–
2 TXD–
3 GND
3 GND
4 RXD+
4 RXD+
5 RXD–
5 RXD–
Table 4–5 COM3/4 switches, Switch 2
Switch 2 – COM3/4 termination
COM Port
Interface
Switch 4 Settings
RS–422/RS–485
no termination
Position 1 Off
Position 2 Off
COM3
RS–422/RS–485
with termination
Position 1 On*
Position 2 On*
RS–422/RS–485
no termination
Position 3 Off
Position 4 Off
COM4
RS–422/RS–485
with termination
Position 3 On*
Position 4 On*
* Default. These switches terminate the network. If
the XE–700 SBC is not at an end of the network, set
these switches to Off .
43