P1157S-881
User’s Manual
AMI BIOS Setup Utility
9
2.2
Serial Ports Interface
This motherboard supports RS-232/422/485 on COM1~COM3 ports and 1 x RS-232 (COM4).
The pin assignments are listed in table below. If you need to adjust these COM ports to work
as RS-232/422/485, please refer to BIOS setting in section 5.4.
Pin
RS-232
RS-422
RS-485
1
DCD, Data Carrier Detect
TX-
RTX-
2
RXD, Receive Data
RX+
N/A
3
TXD, Transmit Data
TX+
RTX+
4
DTR, Data Terminal Ready
RX-
N/A
5
GND
GND
GND
6
DSR, Data Set Ready
N/A
N/A
7
RTS, Request To Send
N/A
N/A
8
CTS, Clear To Send
N/A
N/A
9
No Power/+5V/+12V
N/A
N/A
