An RS323 communication protocol is the oldest and most popular form of serial communication found in applications like printers, computers, etc. Also, other communication forms may include an RS-485 interface and i2C. Undoubtedly, choosing the best serial RS232 serial cable can be a challenge for a few tech enthusiasts. But worry not because we've got you covered. Today's post discusses what a regular RS232 contains in its datasheet, like the pinout and applications of the RS232 connector.
An RS-232 connector
What are rs 232 Connectors?
RS232 connector or a D-type connector is a serial interface port that permits an exchange of data between devices. Its design allows data exchange between Data Communication Equipment (DCE)/MODEM and Data Terminal Equipment (DTE)/ PC. Again, it solves the challenge of parallel communication.
DTE and DCE network illustration
RS232 devices often use serial communication data with a bit-by-bit exchange of data. Moreover, it's a nine-pin connector piece.
Rs 232 Pin Configuration
A DB9/RS232 connector pinout comprises nine pin connections arranged in its port. Initially, it was a 25-pin port terminal, but you can now find a 9-pin port terminal.
Furthermore, both DTE and DCE RS232 ports have similarities only because their data flow direction differs.
9-pin connector in rs-232 pinouts in a male and female connector
Source; Google Creative Commons
The nine pins are in three different categories.
Category 1: Data pins
The first category is data pins that conduct data flow and include;
Pin2/ RXD/ Receiver pin – Receives data or the actual signal.
Pin3/ TXD – It transmits data.
Category 2: Control pins
The second group avoids data loss and establish an interface and consist of;
Pin1/ CD (Carrier Detect) – The MODEM cables set the CD pin to receive an answer transmitted by remote MODEM.
Pin4/ DTR (Data Terminal Ready) – The second pin receives instruction from the PC to prepare the MODEM to connect with a telephone circuit.
Pin6/ DSR (Data Set Ready) – The MODEM often instructs the DSR to inform the PC of its readiness to receive and send data.
Pin7/RTS (Request to Send) – It receives instructions from the PC to notify the MODEM to send data.
Pin8/ CTS (Clear to Send) – MODEM sets the CTS, and through the PC, it becomes ready to receive data/ answering signals.
Pin9/ RI – Lastly, pin9 gets directions from the MODEM cables to let the PC know of a ringing condition.
Category three: Reference pin
A reference pin solely includes the GND/ ground pin, a reference point for all pin voltage signals.
Rs 232 Connectors Features and Specifications
RS 232 connectors have several specifications and features, as we'll discuss below.
- First, you can establish a 2-pin simplex RS232 interface if you need it.
- Then, you can establish the interface to about 50ft distance.
- RS232 connectors use asynchronous communication. Therefore, they don't share clocks between a MODEM and a PC.
- In addition, the wide voltage range of the logic is convenient for users. For instance, logic 0 on the pin has a voltage range from +3V to +15V. Whereas logic 1 ranges from -15V to -3V.
- You can also use RS232 to achieve a maximum data transfer speed of 19 kilobits per second (Kbps).
- Slew rate – A slew rate is a rate of change of signal levels. An RS232 serial connection has a slew rate that can reach 30V/microsecond and 20kbps maximum bitrate.
- Moreover, the RS232 pins can generate a maximum current of 500mA.
- Additionally, the full-duplex interface or an RS232 is efficient.
- Lastly, you can install a MAX232 IC easily and use it to establish the RS2232 interface having microcontrollers.
How to use the RS 232 Connector?
Under any circumstances, we can't directly connect an RS232 connector to a controller. Instead, we use a MAX232 IC.
Circuit diagram with a microcontroller, MAX232, and RS232 serial port
Let's take a look at the circuit diagram above as an example.
We are using a MAX232 converter chip to connect the controller to the female RS232. In the process, the communication voltage can range from -15V to +15V or from -1 volt to +12 volt.
The IC converts high voltage RS232 signals to TTL and vice versa. Since the varying voltage level doesn't suit sensitive electronics, the MAX232 chip becomes a mediator. So, without it, you can cause permanent damages to one of your devices.
- Modem connections,
(RS232 cable connecting to a modem)
- Motor control units,
- Memory devices,
- Telephone lines,
- Automatic control systems,
- Battery management system,
- Stenography or stenotype machines,
- Transfer of serial data,
- Personal computers, and
- Printers where you use one handshaking line and data lines.
(printer and scanner)
Are there any Disadvantages to the RS 232 Connector?
The short answer is yes. You will find some factors not favoring your application for an RS232 connector. They include:
- First and foremost, it lacks a Vcc, a pin required to power devices.
- Additionally, unlike a 12C, you can only connect a single device to a RS 232 connector.
- Moreover, its maximum distance of 50ft and a maximum speed of 19 Kbps disfavors several applications.
- It also has many communication pins. And more hooks equal more noise levels.
- Despite having a wide voltage range, switching between +15V and -15V voltages is quite hard at higher speeds.
- Finally, it requires hardware to aid in the conversion of its high voltage logic to comply with TTL. (TTL/LAN converters involve processor units and controllers).
RS232 connectors operate in several applications. For example, their connection plays a role in uninterruptible power supplies and data storage in personal computers. You can also find them in modems which are peripheral devices.
Do you have any questions or need clarifications? Contact us, and we'll get back to you as soon as possible.