©Sealevel Systems, Inc.
7404e Manual
15
SL9224 02/2017
RS-232 (CA-143 DB-9) Connector Pin Assignments
Signal
Name
Pin #
Mode
GND
Ground
5
TD
Transmit Data
3
Output
RTS
Request To Send
7
Output
DTR
Data Terminal Ready
4
Output
RD
Receive Data
2
Input
CTS
Clear To Send
8
Input
DSR
Data Set Ready
6
Input
DCD
Data Carrier Detect
1
Input
RI
Ring Indicator
9
Input
Please terminate any control signals that are not going to be used. The most common
way to do this is connect RTS to CTS and RI. Also, connect DCD to DTR and DSR.
Terminating these pins, if not used, will help ensure you get the best performance from
your adapter.
