Difference Between RS 232 and RS 485

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 standards of data transmission in common use today. While they may seem similar, there are several points of difference.  

RS 232 vs RS 485 

The main difference between RS 232 and RS 485 is that the maximum cable length in RS 232 is 50 feet. On the other hand, the maximum cable length in RS 485 is 4000 feet. RS 232 has a practical application in laboratory automation surveying. In contrast, a practical application of RS 485 is in computer and automation systems. 

RS 232 and RS 485

RS 232 refers to Recommended Standard 232 that came into existence 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 are used along RS 485 are known as nodes, devices, or stations. 

Comparison Table Between RS 232 and RS 485

Parameters of ComparisonRS 232RS 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 full duplex.RS 485 is half-duplex. 
Ideal for RS 232 is ideal for short 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 that came into existence in the 1960s. The main 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 connect 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 in order to send the signal. Thereafter, 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 easily 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 the connection on 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 in turn allows RS 485 to use linear bus topologies using only two lines. The equipment that are used along RS 485 are known as nodes, devices, or stations. RS 485 is primarily an electrical interface that does not define 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 the use of 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 Differ-ential. 
  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. 

Conclusion

Thus, RS 232 and RS 485 have several visible differences. While RS 232 is full duplex, RS 485 is half-duplex. RS 232 is both cost-effective and time-effective. RS 485 offers faster communication. It  employs three-state logic that allows every transmitter to be deactivated.

The maximum cable length supported by  RS 232 is 15 metres. RS 232 follows a simple method of transmitting data bit by bit over single communication lines. On the other hand, RS 485 has the potential to transmit information from one driver to upto 32 receivers. To conclude, RS 232 and RS 485 vary on several grounds. 

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
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