DB25 connector

The DB25 (originally DE-25) connector is an analog 25-pin plug of the D-Subminiature connector family (D-Sub or Sub-D). As with the DB9 connector, the DB25 connector is mainly used for serial connections, allowing for the asynchronous transmission of data as provided by standard RS-232 (RS-232C). It is also used for parallel port connections, and was originally used to connect printers, and as a result is sometimes known as a printer port (LPT). To avoid confusion, DB25 serial ports on computers generally have male connectors, while parallel port connectors are DB25 female plugs.

DB25 connector


Pins (serial connection)

Pin numberName
2TXD - Transmit Data
3RXD - Receive Data
4RTS - Request To Send
5CTS - Clear To Send
6DSR - Data Set Ready
7GND - Signal Ground
8CD - Carrier Detect
20DTR - Data Terminal Ready
22RI - Ring Indicator

Pins (parallel connection)

Pin numberName
1_STR - Strobe
2D0 - Data bit 0
3D1 - Data bit 1
4D2 - Data bit 2
5D3 - Data bit 3
6D4 - Data bit 4
7D5 - Data bit 5
8D6 - Data bit 6
9D7 - Data bit 7
10ACK - Acknowledgement
11Busy
12Paper Out
13Select
14Auto feed
15Error
16Reset
17Select Input
18Ground
19Ground
20Ground
21Ground
22Ground
23Ground
24Ground
25Ground
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