What is RS 232 and RS 485

Explain RS 232 and RS 485

1 Like

RS232 and RS485 is the communication method which is related to the electronic circuit.

RS232 uses a transmitter and receiver circuit at both ends… while RS845 uses a transceiver at both ends. This is why RS232 determined to use 3 cables, and the RS485 should use 2 or 4 cables.

1 Like

RS-232 is point-to-point only, maximum 2 devices talking to one another. There are software and hardware means of handshaking, to determine who talks when. Hardware handshaking was widely employed for telephone modem communication.

RS-232 is a short distance electrical standard; it maxes out at about 15-20m. RS-232 requires a signal ground connection between both devices.

RS-485 can be point-to-point but was designed for multidrop, multiple devices on one daisy chained (1 to 2 to 3 to 4 . . . 32) network. RS-485 does not tolerate wiring spurs or stubs well. RS-485 requires a signal ground but uses differential transceivers for much better noise rejection than RS-232.

RS-485 uses a tri-state condition when the bus is in idle mode, no device talking. There are no hardware handshaking signals for RS-485. The network bus distance for RS-485 is determined by the baud rate, the higher the baud rate, the shorter distance that is useable. At 90Kb baud and slower, RS-485 will work out to 1500m; at 10Mb the distance is only 5m.

1 Like

HI…RS-232 is a voltage level distinguished correspondence with in any event three wires (RX, TX and Gnd) between two units, Master <-> Slave, Max distance is 15 meters.

RS-485 is a current circle simplex correspondence with typically two wires (An and B) between an expert and a few (32) slave units, Max distance is 1200 meters.

RS-422 is like RS-485 besides here we have four wires (A1, B1 + A2, B2) and the chance of duplex correspondence, 10 slave units, Max distance is 1500 meters.

1 Like

RS-422 is NOT like RS-485. RS-422 is a point-to-point network layer whose devices lack addressability because the hardware connection is a point-to-point connection. RS-422 is the long distance version of RS-232, using balanced, differential drivers to achieve distances that RS-232 cannot with its required signal ground reference (that can have serious common mode differences over long distances).

RS-485 devices are addressable because they can reside on a multidrop network.

1 Like