V A R - E X T - C B 1 0 5 R E V 1 . 2
E X T E N S I O N B O A R D
11 Data Sheet Rev 1.2
3.2
UARTs
3.2.1
RS232 connectors assignment
Connector
VAR-SOM-xM3x
VAR-SOM-MX25
5x2 Header UART A (J5)
UART 2
UART 2
D-Type 9 Male (DTE) UART B
UART 1
UART 3
3.2.2
RS232 connectors pin out
3.2.2.1
RS232
– male D-Type 9 (DTE) – J2
Pin #
Signal
Description
1
NC
2
RX
Serial Data in
3
TX
Serial Data Out
4
NC
5
GND
6
NC
7
RTS
Request to Send - Out
8
CTS
Clear To Send - In
9
NC
3.2.2.2
3.3V Levels UART & RS485
– 2x5 Header – J5
Pin #
Signal
Description
1
NC
2
RX
Serial Data in
3
TX
Serial Data Out
4
Z
RS-485 Tx Signal Negative
5
GND
6
A
RS-485 Tx Signal
7
RTS
Request to Send - Out
8
CTS
Clear To Send - In
9
B
RS-485 Rx Signal Negative
10
Y
RS-485 Tx Signal
