RS232 Connector: Pinout, Circuit and Datasheet

The RS232 connector is a port that allows data to be exchanged between devices. It was created to transfer data between DTE (Data Terminal Equipment) or a computer and DCE (Data Communication Equipment) or a modem. Parallel data exchange posed constraints, which necessitated the use of RS232. RS232 is a serial communication standard that allows data to be sent bit by bit. Although speedier USB (Universal Serial Bus) eventually superseded RS232, it remains popular in some areas. RS232 used to be a 25-pin connector. However, it has since been reduced to merely 9 pins.

RS232 Pinout

• Voltage Levels: RS232 is also used as ground & 5V level. Binary 0 works with voltages up to +5V to +15Vdc. It is called ‘ON’ or spacing (high voltage level) whereas Binary 1 works with voltages up to -5V to -15Vdc. It is called ‘OFF’ or marking (low voltage level).

• Received signal voltage level: Binary 0 works on the received signal voltages up to +3V to +13 Vdc & Binary 1 works with voltages up to -3V to -13 Vdc.

• Line Impedance: The impedance of wires is up to 3 ohms to 7 ohms & the maximum cable length is 15 meters, but the new maximum length is in terms of capacitance per unit length.

• Operation Voltage: The operation voltage will be 250v AC max.

• Current Rating: The current rating will be 3 Amps max.

• Dielectric withstanding voltage: 1000 VAC min.

• Slew Rate: The rate of change of signal levels is termed as Slew Rate. Its slew rate is up to 30 V/microsecond and the maximum bitrate will be 20 kbps.

• Easy to use

• Stable, high speed

• High-cost performance

• ±15-kV ESD Protection

• Low power consumption

• Two Drivers and Two Receivers

• Female DB9 Header

• Low cost

• Widely available and applicable due to its long presence in the telecommunications industry

• Many manufacturers still use RS232 to connect PLCs to devices like HMIs, input and output modules, motor drives, etc.

• Simple wiring and connectors will only max support for 1 driver and 1 receiver

• Suitable for long-distance transmissions

• Similar to microcontroller serial signals; transmit bits one at a time, at specific baud rates, with/without parity and/or stop bits

• Still requires max232 to avoid voltages to destroy microcontroller serial pins

• Personal Computers

• Modems

• Servers

• Memory devices

• Motor control units

• Printers and Scanners

• Telephone lines

• Used basically where serial data transfer is required

RS232 is a serial communication standard that is used to connect a computer and its peripheral devices so that serial data can be sent between them. It obtains the voltage for the data transmission route between the devices. It has a 1.492kbps rate and is utilized in serial communication up to 50 feet. The RS232 is used to connect Data Transmission Equipment (DTE) and Data Communication Equipment (DCE), as defined by the EIA (DCE).

We need a MAX232 IC to convert high voltage signals to TTL and vice versa because we can't connect RS232 directly to the controller. The circuit diagram for it is provided below.

RS232 Circuit

We're using a MAX232 converter chip to link the controller to a female RS232 port. In RS232, the communication voltages can be as high as +15V and as low as -15V. Because voltage levels can't be used in delicate devices, we employ MAX232 as a mediator.

The chip converts controller TTL logic pulses to RS232 voltage level pulses and back. You could permanently damage something if you don't have this chip.

Max 232 serves as the processor's buffer driver. It accepts 0 and 5 volts of digital logic and converts them to the RS232 standard of +10 and -10 volts. Only a few microcontrollers have built-in serial connectors that can connect directly to the PC's RS232 serial port. Many microcontrollers, on the other hand, produce a 0 to 5V output, which necessitates the use of an intermediate buffer circuit to convert the 0 to 5V to the +10 and -10V required by the RS232 connection.

The Max 232 IC has two transmitters and receivers, allowing two serial ports to be linked on the same chip. To generate the needed RS232 standard voltage from the TTL/CMOS voltage, 5 capacitors of 1microFarad each are employed. The transmitters convert TTL/CMOS voltage to RS232 voltage, while the receiver receives RS232 input and transforms it to TTL voltage.

The transmitter pins are linked to the microcontroller and the port so that the input transmitter pin receives TTL input from the microcontroller and the output transmitter pin supplies output to the RS232 port. The receiver pins are linked to the RS232 port in such a way that the input receiver pin gets RS232 standard input from the PC port and the output receiver pin supplies the Microcontroller with TTL input. The transmitter receives data from the Microcontroller and sends it to the RS232 port, while the receiver receives data from the RS232 port and sends it to the Microcontroller.

RS232 Dimensions

After more than 140 years of development, Greenlee has become a supplier of quality tools for the woodworking industry. During these more than 70 years, Greenlee has also been a supplier of quality tools in the electrical industry. More than 20 years ago, Greenlee made a sincere promise to customers. We must use high technology to meet the ever-changing needs of our customers. We have achieved this promise through modern facilities, state-of-the-art production equipment, and enhanced quality assurance programs. The way Greenlee operates today is made up of our plans. To ensure the convenient, fast, and accurate exchange of information between Greenlee and its suppliers and customers, we continue to research and successfully expand the EDI (Electronic Data Interchange) function.