Difference In Rs 232 And Rs 485

Dear Sir,
Let me also know what is RS 232 and RS 485.
Let me know the basic difference between the 232 and 485 and what is the speed of these 2 communication protocols.

"The Electronics Industry Association (EIA) has produced standards for RS485, RS422, RS232, and RS423 that deal with data communications."

Link to the specifications.


The communication protocols you are refering to is vendor specific. It can be ASCII data, binary data, whatever. You'll need to be specific about the vendor.

There are several differences.

From an operations point of view, RS232 operates with a positive and negative voltage and can transmit to a maximum distance of 50 feet without a repeater.

RS485 operates at 5 VDC and can transmit at a distance to a maximum distance of 4000 feet.

If your RS485 is set up for multidrop, then you can network multiple devices together.

In the Entertron world, our RS485 in conjunction with ModBus RTU we can have an ePLC network of a master and 16 slaves for two of our products and 32 slaves for the Elite-2000. They are connected via RS485 multidrop.

Hope this helps.

God Bless,

Just to be absolutely sure that you understand - RS232 and RS485 are electrical specifications on how to transmit high and low states from one place to another using wire. The specification says nothing about the meaning of the On/Off states. (This "nothing about the meaning" is referring only to the data lines. RS232 establishes timing and meaning to the control lines between the Data Terminal Equipment/Computer (DTE) and a modem (Data Communicating Equipment or DCE))

Your other post on Modbus is a protocol which attaches specific meaning to the On/Off states. This particular protocol can be sent using a variety of electrical methods.

In between these two levels is one which describes Start Bits, Stop Bits, Baud Rates, Parity Bits etc.

So to be correct, you may say that RS232 and RS485 are serial communication interfaces not protocols.

ayman metwally said:

So to be correct, you may say that RS232 and RS485 are serial communication interfaces not protocols.

Click to expand...

RS232 and RS485 are indeed specifications for serial data interfacing (EIA). Some vendors may adopt the titles to describe their use of them. A-B is one of them with the "RS485".

AB confused the issue by naming a protocol DH485 which originally used the RS485 electrical interface. Unfortunately the same protocol can be sent over RS232 lines in a 1-1 mode. This leads to many newcomers hopelessly confusing the protocol DH485 with the electrical interface RS485.