Serial Port Pin Assignments

Pin no.

Signal name

Direction

Description

1

NC

No connection

2

TX

O

Transmitted data

3

RX

I

Received data

4

RTS

O

Request to send

5

CTS

I

Clear to send

6

DSR

I

Data set ready

7

GND

Signal ground

8

DCD

I

Data carrier detect

9-19

NC

No connection

20

DTR

O

Data transmit ready

21

NC

No connection

22

RI

I

Ring indicator

23-25

NC

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