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IoT Gateway

RS485 Device Wiring

How to wire HPzenAi field devices to the gateway over RS485.

RS485 basics​

RS485 is a two-wire differential bus used to connect water meters, level sensors, energy meters, and relay controllers to the gateway. Up to 32 devices can share one RS485 bus segment.

Wiring diagram​

Steps​

  • Gateway RS485 terminal A → Device RS485 terminal A (connect all A terminals together)
  • Gateway RS485 terminal B → Device RS485 terminal B (connect all B terminals together)
  • Use shielded twisted-pair cable (STP, minimum 22 AWG) for runs over 5 m.
  • Maximum recommended cable length: 1,200 m at 9600 baud.
  • Terminate with a 120 Ω resistor between A and B at each end of the bus.

Device address configuration​

Each RS485 device must have a unique address on the bus (typically 1–32). Set the address using the DIP switches or rotary dial on the device, or via the app before wiring into the bus. The gateway scans and auto-discovers all addressed devices.

Powering field devices​

RS485 carries communication only — not power. Each field device requires its own 12V DC supply. Use HPzenAi power adapters or a shared 12V DIN rail PSU for panel installations.