Connect the devices on the RS-485 bus in a point-to-point
configuration, with the (+) and (-) terminals from one device connected
to the corresponding (+) and (-) terminals on the next device.
Use a shielded 2 twisted pair
or 1.5 twisted pair RS-485 cable to wire the devices. Use one twisted
pair to connect the (+) and (-) terminals, and use the other insulated
wire to connect the C terminals.
The total distance for devices
connected on an RS-485 bus should not exceed 1200 m (4000 ft).
||Common. This provides the voltage reference (zero volts) for
the data plus and data minus signals
||Shield. Connect the bare wire to this terminal to help suppress
signal noise that may be present. Ground the shield wiring at one
end only (either at the master or the last slave device, but not both).
||Data minus. This transmits/receives the inverting data signals.
||Data plus. This transmits/receives the non-inverting data signals.
NOTE: If some devices in your RS-485 network do not have the
C terminal, use the bare wire in the RS-485 cable to connect the C
terminal from the meter to the shield terminal on the devices that
do not have the C terminal.