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).
D-sub 9 Male
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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