DB9 Connectors | Tech Info Home Page |

General Information - 

A typical cable using DB9 connectors made by CompuCable.

The DB9 connector is used by serial port devices. On a typical PC the DB9 connector is located on the back of the computer and is assigned to one of the Com Ports. It has 9 pins arranged in two rows one on top of the other. The top row has 5 pins and the lower row has 4 pins.

Cables using DB9 plugs are found on the "Modem Cables" page.

Pin Signals

• Pin 1 - Received Line Signal Detect
• Pin 2 - Received Data
• Pin 3 - Transmitted Data
• Pin 4 - Data Terminal Ready (DTR)
• Pin 5 - Signal Ground
• Pin 6 - Data Set Ready (DSR)
• Pin 7 - Request to Send (RTS)
• Pin 8 - Clear to Send (CTS)
• Pin 9 - Ring Indicator (RI)

 

Male Connector Serial Interface Modem Cable Pin Definitions

DB-25 -------------  DB-9 ------------- Circuit  ---------------- Function  ------------------------- Signal Source  Computer/Modem ----------------------------- 1 -- AA Chassis Ground Both 2 3 BA Transmitted Data Computer 3  2 BB Received Data Modem 4 7 CA Request to Send Computer 5 8 CB Clear to Send Modem 6 6 CC Data Set Ready Modem 7 5 AB Signal Ground Both 8 1 CF Carrier Detect Modem 12 -- SCF Speed Indicate Modem 20 4 CD Data Terminal Ready Computer 22 9 CE Ring Indicate Modem

 

 

Loopback Pinout

1-7-8
2-3
4-6-9

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