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Difference Between RS232 and RS485

What is RS232?

RS232 is a form of serial data transmission. In other words, it is a communication protocol. With its standard 9 pin DB9 cable, it was once most used form of data transmission.

9 pin DB9 male and female cable


For easier way to understand of the communication protocol between devices, RS232 cable was once widely used on computers connecting to the old printers (before the time it was supported by USB). Note that RS232 itself are separated into 2 types. One is named as Data Terminal Equipment (DTE), and the other is named as Data Communications Equipment (DCE). The reason RS232 is separated into 2 types is because two DTE or two DCE devices will not be able to talk to each other. The only way to communicate between them will be a connection of DTE to DCE in a network. With this, RS232 cable comes with a DTE (male) and DCE (female) in each end, as shown in the image above.


As of now, RS232 are still widely used on Programmable Logic Control (PLC), which is an industrial computer that has been ruggedized and adapted for the use of manufacturing line, such as assembly lines, machines, robotic devices and others. RS232 are used to communicate with other modules in here. Usually it can be seen on the robotic device at a production line, connecting to its very own PLC.

Custronics LED ASCII RS232 or RS485 Display Panel

Actual size: 690mm x 210mm x 80mm

Color red, format: 2 x 10CH, character height: 70mm

Available input: RS232 / RS485 (Modbus RTU / Modbus ASCII)



What is RS485?

Same as RS232, RS485 is also a form of communication protocol, but faster. It uses same DB9 connector as RS232, however, RS485 does not have an actual standard connector. In some applications, terminal strip or terminal block is used, allowing a RS485 to be a more versatile form of communication.

Terminal Block



What are the difference between RS232 and RS485?

RS485 are very much differ from RS232 in terms of communication distance, susceptible to electrical noise, amount of devices can be connected and the speed of data transmission.


Communication distance

The maximum distance of RS232 can support is 15 meters. The distance can be extended considerably with a slower data rates. As for RS485, the maximum distance is 1200 meters. This is reasonable to be used if the device, equipment or machines are meant to operate at a distance from the transmitter.


Susceptible to electrical noise

RS232 can operate very well on a single-ended line but is too fragile to electrical noise with different potential levels. It may end up with a data corruption. RS485 is different as it operates on a differential-voltage, it is capable to prevent from electrical noise interference. This is also one of the reason it can support for a further distance of 1200 meters.


Amount of devices can be connected

As mentioned earlier, RS232 can only be communicated between DTE and DCE in a network, which is a sender and a receiver. RSS485 is designed for a multi-point system and can connect up to 32 devices to a transmitter.


The speed of data transmission

As RS232 can perform well with a shorter distance, it has a transmission speed of 1mb/s. For RS485, it has a data transmission speed of up to 10mb/s, but if it is at a maximum of 1200 meters, the transmission speed will be 100kb/s.


Custronics LED ASCII RS232 or RS485 Display Panel

Actual size: 1330mm x 370mm x 80mm

Color red, format 2 x 16CH, character height: 110mm

Available input : RS232 / RS485 (Modbus RTU / Modbus ASCII)


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