What Is a D-Sub Connector?
A D-Sub connector is a classic multi-pin connector named for the D shape of the metal shell surrounding its pins. The D shape ensures the plug goes in only one way.
Naming
In names like DB9 and DE-15, the number indicates the pin count. The pins are arranged in 1–3 rows. The metal shell serves both as mechanical protection and as shielding/grounding.
| Type | Pins | Typical Use |
|---|---|---|
| DB9 | 9 | RS-232 serial port |
| DB25 | 25 | Old parallel/serial port |
| VGA (DE-15) | 15 | Analog monitor |
Where Is It Used?
RS-232 serial communication (DB9), old monitor connection (VGA), industrial devices and test/measurement equipment. Because of its robustness it's still common in industry.
Locking Screws
The screws beside D-Sub plugs fix the connector to the other side, preventing it from coming out with vibration or pulling; this is an important reason for its industrial reliability.
High-Density Types
To fit more pins in the same body size, there are "high-density" D-Sub types where the pins are arranged in three rows; the VGA (DE-15) is its best-known example. This lets 15 pins be carried in the standard DB9 body size, but the pins are thinner and carry lower current.
Common Mistakes
- Gender: if male/female of the same pin count are mixed up, no connection is made.
- Pinout: if TX/RX are swapped in RS-232, there's no communication (a null-modem may be needed).
- Screws: if the fixing screws aren't tightened, the connection loosens.
Frequently Asked Questions
Is VGA also a D-Sub?+
Is DB9 still used?+
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