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RS485 Serial Communication Protocol ?

Generally , the rs485 serial communication protocol is a serial transmission medium developed for use at longer distances, in noisy environments, where much higher speed is required, where much more transceivers are required. The RS-485 protocol also sets the standard only for the transmission layer. The protocol to be used in the software layer and the connector types to be used are shaped according to the user's request. In this context, what is rs485 and how is it provided?

RS485 Serial Communication Protocol

RS- 485 Pins

The answer to the question of what is rs-485 in the full sense is based on the logic of transmitting data over the line with the rs-485 serial communication protocol, the basic part of which is balanced. In this respect , over rs-485 , data is transmitted over 2 cables called A and B. These two ends are lines that are balanced. In the balanced lines, there are differential drivers in the transmitters and differential receivers in the receivers.

In general, the logic of the line, which is also balanced, proceeds as follows. If noise is transmitted from the same path to these 2 lines in the transmission environment while the data is being transmitted, and the difference amplifiers located at the entrance of the receiver will take the difference of these 2 lines, the total noise amount at the input becomes zero. Accordingly, the effect of the noise on the data along the line to the receiver input is minimized.

RS485 Serial Communication Protocol Operation

RS-485 Half Duplex – Full Duplex

Generally, using twisted cable in rs-485 serial communication and as a result correct termination is achieved at very high speed over very long distances. The twisted cable also creates a phase difference between the 2 screws, helping to reduce the noise to a large extent. Moreover; The termination process will also reduce the reflection in the transmission medium to a minimum.