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Insight - How RS232 Connector Works

Written By: 

Abhimanyu Mathur

RS 232 Connector

                                                                        Fig. 1: RS232 Connector

Serial interfacing is one of the most common protocols to make two electronic gadgets communicate. In such interfacings, the data is sent sequentially and bit by bit. RS232 is one sub type of serial interfacing that was introduced in the year 1932. Available in 9 pin and 25 pin configurations, RS 232 pins allow data exchanges at the maximum of 256kbps.

Some well known applications of these connectors include linking modems to computers and other micro controller based UART electronic gadgets. Of course, such an interfacing would require different types of connectors; in this case, RS232 connectors are used. The Insight covers a conventional 9 pin female RS232 connector. Let’s find out the outer and inner details of it.

Image of Female 9-Pin RS 232 Connector

Fig. 2: Image of Female 9-Pin RS 232 Connector


Input Pins: Image 02 shows a 9 pin RS 232 connector. The pin inputs are etched on a plastic molding which is encased in a metal casing. The pins are numbered by the manufacturer (as can be seen in the image). Their functions are mentioned below:

Pin 1: Data Carrier Detect

Pin 2: Received Data

       Pin 3: Transmitted Data

       Pin4: Data Terminal Ready

       Pin5: Signal Ground

       Pin6: Data Set Ready

      Pin7: Request to send

         Pin8: Clear to send

        Pin9: Ring Indicator

 The metal casing has circular cut sections at its end so that it is easily mounted.

Output Pins & Moldings

Output Pins

Output Pins

Fig. 3: Output Pins

Output Pins: Corresponding to the front, 9 output pins are located on the reverse side of the connector. Like the input pins, output pins are also numbered.

Plastic Moldings

Dissembled Casing and Plastic Structure that Houses Connector Pins

Fig. 4: Dissembled Casing and Plastic Structure that Houses Connector Pins

Plastic Moldings: The casing is split into two to reveal the plastic structure which houses the pins.

Pin Placement & Structure

Pin Placement & Structure

Two Parts of Plastic Molding that Holds the Pins

Fig. 5: Two Parts of Plastic Molding that Holds the Pins


 Pin Placement: The plastic moldings are further opened to get a better view of the pins. The image above shows the two parts holding the pins.

Image Indicating Shape of Pins

Fig. 6: Image Indicating Shape of Pins


Pin Structure: A “Y”-shaped pin is plucked out of the plastic moldings. The cut sections made at the plastic moldings are seen to have different opening for different ends of the plastic pins. 

Fig. 7: "Y"-shaped Pin


The pins are in a “Y” shaped structure. The part which is soldered has a curved end to facilitate strong soldering bonds, while the part which gets the input pin has two closely placed arms that aid in proper holding of the device.