RS 232 vs RS 485: Difference and Comparison

Physical protocols of information are pivotal in today’s technology-driven era. They are necessary to ensure that data transmission takes place following certain standards.

RS 232 and RS 485 are two recommended data transmission standards in everyday use today. While they may seem similar, there are several points of difference.  

Key Takeaways

1. RS-232 supports point-to-point communication, while RS-485 allows multidrop configurations with up to 32 devices.
2. RS-485 provides longer communication distances (up to 4,000 feet) than RS-232 (up to 50 feet).
3. RS-485 offers better noise immunity and signal integrity, making it suitable for industrial environments.

RS 232 vs RS 485 

RS-232 (Recommended Standard 232) is a communication standard defines the electrical characteristics of signals used for serial communication between data communication equipment. RS-485 (Recommended Standard 485) is a communication standard used for serial communication between multiple devices.

RS 232 refers to Recommended Standard 232, which existed in the 1960s. The operation mode of RS 232 is single-ended and unbalanced.

In addition, RS 232 employs only two devices in data transmission: driver and receiver.  An advantage of RS 232 is that it is widely available and relatively easy to use.

RS 485 is a standard defining the electrical characteristics of the senders and receivers that are used in serial communication networks.

RS 485 is a versatile connector owing to its noise immunity factor. In addition, the equipment that is used along RS 485 is known as nodes, devices, or stations. 

Comparison Table

Parameters of Comparison	RS 232	RS 485
Driver and Receiver	There is only one driver and one receiver in RS 232.	There is one driver and 32 receivers in RS 485.
Maximum Data Rate	The maximum data rate in RS 232 is 460kb/s.	The maximum data rate in RS 485 is 30mb/s.
Duplex Type	RS 232 is ideal for short-distance communications.	RS 485 is half-duplex.
Ideal for	RS 485 is ideal for long-distance communications.	RS 485 is ideal for long distance communications.
Cost	RS 232 is less expensive as compared to RS 485.	RS 485 is more expensive as compared to RS 232.

What is RS 232?

RS 232 refers to Recommended Standard 232, which came into existence in the 1960s. The primary purpose of RS 232 was to ensure serial communication transmission of data.

In other words, RS 232 is a way of transiting data across different devices. RS 232 follows a simple method of transmitting data bit by bit over single communication lines. 

 RS 232 is suitable for long-distance communications. RS 232 employs only two devices in data transmission: driver and receiver. The maximum transmission rate of  RS 232 is 460 Kbps.

In addition, the maximum cable length supported by  RS 232 is 15 metres. The operation mode of RS 232 is single-ended and unbalanced.

RS 232 connects Data Transmission Equipment and Data Communication Equipment. For instance, RS 232 may associate a computer with a modem.

The first step in data transmission involves a request generated by RTS in the DTE for the data to be sent. Moving further, the DCE receives the request. Then, CTE performs the function of clearing the path to receive the information. 

Once that data has been cleared, CTS will send a signal to DTE to send the password. After that, the process of data transmission begins.

An advantage of RS 232 is that it is widely available and relatively easy to use. Moreover, it is cost-effective. Thus, it is both easily affordable and readily available in the consumer market. 

What is RS 485?

RS 485 is a standard defining the electrical characteristics of the senders and receivers that are used in serial communication networks. The electric signalling in RS 485 is balanced.

Moreover, RS 485 supports multipoint systems. Thus, RS 485 has a practical application in electrically noisy environments and over long distances. 

RS 485 came into existence in 1998. Since RS 485 allows connecting multiple devices on the same bus, it is widely used in industrial and automation spaces.

Another practical application of RS 485 is in theatres wherein several devices are spread out in a large area. In addition, RS 485 is a versatile connector owing to its noise immunity factor. 

RS 485 employs three-state logic that allows every transmitter to be deactivated. This, allows RS 485 to use linear bus topologies using only two lines.

The equipment that is used along RS 485 is known as nodes, devices, or stations. RS 485 is primarily an electrical interface not defining a communication protocol. 

An advantage of RS 485 is the relatively less time of communication between the sender and the receiver when there are 32 or fewer controllers.

However, RS 485 is not ideal for transmitting large amounts of data. Moreover, RS 485 requires special cables, and ordinary cables are not functional. 

Main Differences Between RS 232 and RS 485

1. The mode of operation in RS 232 is single-ended. In contrast, the mode of operation in RS 485 is Differential. 
2. There is only one driver and one receiver in RS 232. On the other hand, there is one driver and 32 receivers in RS 485.
3. While the maximum cable length in RS 232 is 50 feet, the maximum cable length in RS 485 is 4000 feet.
4. The maximum data rate in RS 232 is 460kb/s. On the other hand, the maximum data rate in RS 485 is 30mb/s.
5. RS 232 has a practical application in laboratory automation surveying. On the other hand, a practical application of RS 485 is in computer and automation systems. 

References

1. https://en.wikipedia.org/wiki/RS-485 
2. https://www.seeedstudio.com/blog/2019/12/06/what-is-rs485-and-its-difference-between-rs232/#:~:text=RS232%20is%20more%20than%20able,RS485%20transmits%20at%20100Kb%2Fs.