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D-sub 9 Connector

The DE-9 D-sub 9-pin connector is often mistakenly referred to as the "DB-9" connector.  The "E" refers to the shell size.  A "DB-25" connector has a "B" size shell, but the common nine-pin connector is smaller and has an "E" size shell.  

This  connector (regardless what you call it) is used for a variety of purposes.  Two common applications are RS-232/EIA-232 (serial) connections (including UPS cables), and a variety of video interfaces on the IBM PC.  

Here's a good set of figures for D-sub 9 male and female connectors, as viewed from the pin side (not the solder side).

DB-9 Male

D-sub 9 Male

DB-9 Female

D-sub 9 Female

Pins commonly used for RS-232/EIA-232 (serial):

DB-25 D-sub-9 Signal Direction Signal Name
1   x Protective Ground
2 3 DTE-to-DCE Transmitted Data
3 2 DCE-to-DTE Received Data
4 7 DTE-to-DCE Request To Send
5 8 DCE-to-DTE Clear To Send
6 6 DCE-to-DTE Data Set Ready
7 5 x Signal Ground
8 1 DCE-to-DTE Received Line Signal Detector (Carrier Detect)
20 4 DTE-to-DCE Data Terminal Ready
22 9 DCE-to-DTE Ring Indicator

Click here to see the pinout of DB-25 connectors.

 

Common Null-Modem Connection

Signal Name DB-25 Pin D-sub 9 Pin   D-sub 9 Pin DB-25 Pin  
FG (Frame Ground) 1 - X - 1 FG
TD (Transmit Data) 2 3 - 2 3 RD
RD (Receive Data) 3 2 - 3 2 TD
RTS (Request To Send) 4 7 - 8 5 CTS
CTS (Clear To Send) 5 8 - 7 4 RTS
SG (Signal Ground) 7 5 - 5 7 SG
DSR (Data Set Ready) 6 6 - 4 20 DTR
CD (Carrier Detect) 8 1 - 4 20 DTR
DTR (Data Terminal Ready) 20 4 - 1 8 CD
DTR (Data Terminal Ready) 20 4 - 6 6 DSR

Click here to see the pinout of DB-25 connectors.

 

D-sub 9 pins commonly used for the IBM-PC CGA (color) video:

Pin Description
1 Signal ground
2 Signal ground
3 Red video
4 Green video
5 Blue video
6 Signal intensity
7 Unused
8 Horizontal sync
9 Vertical sync

Click here to see the pinout of HD-D-sub15 connectors (used for VGA).

D-sub 9 pins commonly used for the IBM-PC EGA (color) video:

Pin Description
1 Signal ground
2 Secondary red
3 Red video
4 Green video
5 Blue video
6 Secondary green / signal intensity
7 Secondary blue / Monochrome
8 Secondary blue / horizontal sync
9 Vertical sync

Click here to see the pinout of HD-DB-15 connectors (used for VGA).

D-sub 9 pins commonly used for the IBM-PC MGA/HGA (monochrome) video:

Pin Description
1 Signal ground
2 Signal ground
3 Not used
4 Not used
5 Not used
6 Signal intensity
7 Video signal
8 Horizontal sync
9 Vertical sync

 

D-sub 9 pins sometimes used for VGA (color) video:

Pin Description
1 Red Video
2 Green Video
3 Blue Video
4 Horizontal Sync
5 Vertical Sync
6 Red Ground
7 Green Ground
8 Blue Ground
9 Sync Ground

Click here to see the pinout of HD-D-sub 15 connectors (used for VGA).

 

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This site last updated 7/11/2008