RS232 Pinout and diagram of DB9 connector
commonly used for serial ports RS-232 communication via Serial Port
Software to manage your RS232 devices
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RS232 Pinout DB9 male computer

Pinout diagram of DB9 connector

Pin

Sig.

Signal Name

DTE (PC)
1
DCD
Data Carrier Detect
in
2
RXD
Receive Data
in
3
TXD
Transmit Data
out
4
DTR
Data Terminal Ready
out
5
GND
Signal Ground
-
6
DSR
Data Set Ready
in
7
RTS
Request to Send
out
8
CTS
Clear to Send
in
9
RI
Ring Indicator
in
The DTE (computer) has the male connector and the DCE (peripheral) has the female

 

RS-232 Maximum Cable Length
The maximum cable length for RS-232 is around 50ft, but in practise depends on baud rate, cable specific capacitance and ambient noise.
The table below contains some rules-of-thumb from experiments done by Texas Instruments.

Baud rate

Maximum cable length
19200
50ft
9600
500ft
4800
1000ft
2400
3000ft