dfrobot RS485 Wind Vane Direction Sensor

AI context

Dense context for pasting into a model prompt — addresses, pinout, voltages, tolerances and the vendor's reference circuit.

PART: DFRobot RS485 Wind Vane Direction Sensor, SKU SEN0482. An aluminium-alloy wind vane with a low-inertia fin and a Hall sensor element, read by a module that speaks Modbus RTU over RS485. The vendor names no controller part number, so part is null.
SUPPLY: 7 V to 24 V DC on the red and black wires - this is not a 3.3 V or 5 V part and cannot be powered from a microcontroller rail.
BUS: RS485 half-duplex, Modbus RTU protocol. The library DFRobot publishes for it initialises the port and reads wind direction in one call; the vendor gives no baud rate, slave address or register map on the product page or wiki, so those must come from the vendor's own library or a bus scan rather than from this entry.
PINOUT: pad 1 red wire, positive supply; pad 2 black wire, negative supply / ground; pad 3 yellow wire, RS485+/A/T+; pad 4 green wire, RS485-/B/T-. DFRobot labels the same pair both RS485 and T (the RS485 letter and the Modbus T/R naming) on one line.
MEASUREMENT: 16 directions over a full 360 degrees, with a start-up wind speed of 0.3 m/s or less, so the vane reads direction even in very light air.
CABLE: 2.5 m of lead is supplied, which is the whole bus stub - there is no separate connector on the vane, so the four wires are the only interface.
TRAPS: (1) 7-24 V DC supply, not logic-level - a 5 V rail will not drive it. (2) RS485 needs a transceiver on the controller side plus a common ground; A/B naming is swapped between some vendors, so identify by the pair, not by the letter. (3) DFRobot publishes no default slave address or baud rate, so two vanes on one bus cannot be assumed distinguishable out of the box.