Rs485 - odot -S1E1V2.0 User Manual

The RS422 communication wiring diagram is shown in the figure:

3. RS485

Since the RS-485 is developed from the RS-422, many electrical provisions of
the RS-485 are similar to those of the RS-422.If they all adopt the balanced
transmission mode, they all need to connect the final resistance on the transmission
line, etc. The RS-485 can adopt two - wire and four - wire mode, and the two - wire
system can realize real multi - point two - way communication.
RS485 is a standard for defining the electrical characteristics of drivers and
receivers in a balanced digital multipoint system, using a combination of balanced
drivers and differential receivers for enhanced common-mode dry resistance, i.e.,
good noise interference resistance. Because the semi-duplex network composed of
RS485 interface generally adopts the wiring mode of two-wire system and adopts
differential signal to transmit data, the voltage difference between the two lines is
-(2-6)V to represent logic "0 ", and the voltage difference between the two lines is
+(2-6)V to represent logic "1".
RS485 signal transmission distance is related to communication baud rate, the
higher the baud rate, the shorter the transmission distance, under the condition of the
baud rate is not higher than 100 KBPS, theory of the maximum communication
distance is about 1200 meters, in the process of practical application, Due to
electromagnetic interference and other factors, often cannot meet the maximum
communication distance, if in a long-distance communication, please reduce the baud
rate, to reduce the signal during transmission by external electromagnetic interference,
please use twisted-pair shielded cable as a communication cable.
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