DB9 Connector

What Is DB9 Connector?

The DB9 connector is a popular type of electrical connector. And the DB9 female connector and DB9 male connector are used widely in the world. D type data interface connector is the stand of interface for connecting electronic equipment. For example, the computer and keyboard, mouse and etc. Because of the shape of it is closed to the letter “D”, so people usually call it as the D type connector. It has the smallest “footprint” of the D-subminiature connectors. And with 9 pins (male connector) or 9 holes (female connector), so it was called DB9 connector.

Most people think the DE-9 D-sub 9-pin connector is the DB-9 connector. The “E” means that its shell size in accordance with pins. And levels are “A”, “B”, “C”, “D”, “E”. “A” level with 15 pins, “B” is 25 pins, “C” is 37 pins, “D” is 50 pins, “E” is 9 pins. The DB25 connector has the “B” level shell size, but the common nine-pin connector is smaller and has the “E” size shell. Because personal computers first used DB25 connectors for their serial and parallel ports, when the PC serial port began to use 9-pin connectors, they usually were labeled as DB9 instead of DE9 connectors. Due to the ignorance of the fact that B represented the size of the shell. As time went by, the terms for DB9 AND DE9 have become synonymous. Although this point is not correct in the technology, but the trend right now is that people DE9 connectors sold as DB9 connectors in the stores.

DB9 Connector Applications

DB9 connectors were very popular on personal computers and servers before. People usually use it combine with the EIA/TIA 232 serial interface standard, which determined the function of all nine pins as a stand. Then a lot of companies can use this technology to make own products. And DB9 connectors are a good part of connecting serial peripheral devices. Such as the keyset, computer mice, joysticks, light pen, graphics tablet and etc. By the way, they must use the DB9 cable assemblies to achieve the purpose of data connectivity. And in recent years, people use new technology to replace it. Such as the USB, PS/2, Firewire, and etc. But, lots of companies still use this technology for serial communication to cut the cost.

The Definition of DB9 Connectors Serial Interface

When you use the male connector and female connector to connect MAX 232, you will recognize there is nothing different for each other. But that is not correct. If you look at the above picture carefully, you will find the truth. In the connecting of male connector and female connector, the number 2 pin of male connector is connecting number 2 hole of female connector. If you take the definition of it, you will understand for this way which is receiving end connecting receiving end and sending end connecting sending end. So, you can use this way to understand for the male connector. But the female you need to think it at the receiving type of serial interface definition. For example, you can understand the number 2 hole need to connect the data receiving part of male connector.

If you use the male connector, the way of connecting is: Max232 (14,7) need to connect number 3 pin of male connector; MAX232 (13,8) connector number 2 Pin of male connector.

And the method of connecting for female connector is: MAX232 (14,7) connect number 2 hole of female connector; MAX232 (13,8) connect number 3 pin of male connector.

There are three types as below of connecting wire that we annual use.

  1. Two ending parts are female connectors.
  2. Two ending parts are male connectors.
  3. One ending part is male connectors and another ending part is female connector.