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A and B terminals of the last RS485 to ensure communication impedance matching, and the terminal matching
resistance is generally between 120Ω-10kΩ, and may vary with different wiring. The above figure is the schematic
diagram of using a three-core shielded line, the shielding lay is connected with ground, and the G1 terminals of each
device are connected in parallel.
8 Debugging and Maintenance
8.1 Operation instructions
1) Check whether the power line is properly connected before powering on.
2) After powering on, ensure that the power indicator light (POWER) is lit, and that the RUN light (RUN) begins
to flicker at an interval of 1 second.
3) Communication establishment
a) Correctly connect the RS485 bus and connect it to the upper computer.
b) The upper computer issues commands according to the station number and baud rate of the module in the
protocol format. At this time, the communication indicator light of the module flashes, indicating that the
module has received the command of the upper computer and responded, that is, the communication has
been established.
8.2 Debugging
1) Check whether the power supply is properly connected before powering on.
2) After powering on, observe whether the power light is on, if not, it means that the power is not connected.
3) Observe whether the RUN light flashes, if not, it means that the module does not run normally.
4) Only when the communication indicator light flashes will it indicate that the communication is established.
5) Set the query time interval of the upper computer. As the bus is the half-duplex mode, the upper computer
should set an appropriate time interval, which should be determined according to the module reply command
length and the baud rate. Improper time interval setting will lead to communication failure.
