Schneider Electric HRB1684301-01 RS-485 wiring, RS-485 cable, RS-485 maximum cable length

Chapter 2—Hardware reference PowerLogic™ PM5500 series user manual

RS-485 wiring

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.

RS-485 wiring

C

-

+

Master Slaves

-

+

120 Ω

D0 (-)

D1 (+)

120 Ω

RS-485 cable

Use a shielded 1.5 twisted pair or 2 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.

RS-485 terminals

CCommon. 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 signal.

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 terminal on the devices that do not have the C terminal.

RS-485 maximum cable length

The total distance for devices connected on an RS-485 bus should not exceed 1200 m (4000 ft).

RS-485 network configuration

After you have wired the RS-485 port and powered up the meter, you must configure the serial communications port in order to communicate with the meter.

Each device on the same RS-485 communications bus must have a unique address and all connected devices must be set to the same protocol, baud rate, and parity (data format).

NOTE: To communicate with the meter using ION Setup, you must set the serial site and all connected devices in the RS-485 network to the same parity setting.

For meters that do not have a display, you must first wire and configure each one separately before connecting these meters to the same RS-485 bus.

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