Device Connection; 1Rs485 Connection - Ebyte ME31-XAAX0440 User Manual

Chengdu Ebyte Electronic Technology Co., Ltd. ME31- XAAX0440 _User Manual

1.2 Device connection

2.2.1RS485 connection

Note: When the
485 bus high-frequency signal is transmitted, the signal wavelength is shorter than the transmission line, and the signal will form a
reflected wave at the end of the transmission line, which will interfere with the original signal. Therefore, it is necessary to add a terminal resistor at the end of the
transmission line so that the signal does not reflect after reaching the end of the transmission line. The terminal resistance should be the same as the impedance of
the communication cable, the typical value is 120 ohms. Its function is to match the bus impedance and improve the anti-interference and reliability of data
communication.
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