Serial Port Pin Assignments
Pin no.
Signal name
1
NC
2
TX
3
RX
4
RTS
5
CTS
6
DSR
7
GND
8
DCD
9-19
NC
20
DTR
21
NC
22
RI
23-25 NC
Direction Description
—
No connection
O
Transmitted data
I
O
Received data
Request to send
I
Clear to send
I
Data set ready
—
Signal ground
I
Data carrier detect
—
No connection
O
Data transmit ready
—
No connection
I
Ring indicator
—
No connection
Note: The following current loop functions are not supported:
Pin 9:
+Transmit current loop data
Pin 11: -Transmit current loop data
Pin 18: +Receive current loop data
Pin 25: -Receive current loop data
B-8 Specifications