PC Com Port - EIA-574 RS-232/V.24 pin out on a DB-9 pin used for asynchronous data

Serial (RS232) port cable and signals

X.21 interface on a DB 15 connector

X.21 interface on a DB 15 connector

X.21 interface on a DB 15 connector

RS232D uses RJ45 type connectors (similar to telephone connectors)

 

RS232D uses RJ45 type connectors (similar to telephone connectors)
Pin No. Signal Description Abbr. DTE DCE
1 DCE Ready, Ring Indicator DSR/RI
2 Received Line Signal Detector DCD
3 DTE Ready DTR
4 Signal Ground SG    
5 Received Data RxD
6 Transmitted Data TxD
7 Clear To Send CTS
8 Request To Send RTS

This is a standard 9 to 25 pin cable layout for async data on a PC AT serial cable 

This is a standard 9 to 25 pin cable layout for async data on a PC AT serial cable

Some applications require more pins than a simple async. configurations.

Some applications require more pins than a simple async. configurations.