What is the difference between a wind speed sensor and a wind direction sensor?

A wind speed sensor (anemometer) measures how fast the wind is blowing, expressed in m/s or km/h. A wind direction sensor (wind vane) measures which compass direction the wind is coming from, expressed in degrees (0–360°). The FST201 is a three-cup anemometer: as the cups rotate, a Hall effect sensor inside the housing generates pulses that are converted to a 4–20 mA signal proportional to wind speed. The FST202 is a mechanical vane: as it rotates into the wind, an internal resistive element produces a 4–20 mA signal proportional to the compass angle. Most monitoring installations use both sensors together.

How does a 4–20 mA wind sensor connect to a PLC or data logger?

Both the FST201 and FST202 use an industry-standard three-wire 4–20 mA current loop. Two wires carry the 12–30 VDC power supply; the third carries the signal current. Your PLC or data logger reads the current on its analogue input channel: 4 mA = minimum reading (0.5 m/s or 0°), 20 mA = maximum reading (50 m/s or 360°). No external signal conditioner, transmitter, or protocol converter is needed — wire the three cores directly to the analogue input terminal block. Both sensors use a standard M12 four-pin weatherproof connector; any compatible M12 male cable can be used for field installation.

What does IP65 mean for a wind sensor, and is it adequate for South African conditions?

IP65 per IEC 60529 means the enclosure is fully dust-tight (digit 6 — no dust can enter) and protected against water jets from any direction (digit 5). For South African outdoor installations — including the Western Cape's coastal salt spray, the Highveld's intense summer thunderstorms, and the Karoo's severe dust conditions — IP65 is the correct and sufficient protection class for a mast-mounted wind sensor. Submerged or high-pressure wash-down environments would require IP67 or IP68, but those scenarios do not arise for wind sensors mounted on poles or rooftops.

What is the measuring range of the FST201 wind speed transmitter?

The FST201 measures 0.5 to 50 m/s (1.8 to 180 km/h). On the Beaufort scale, this spans from a light breeze (Beaufort 2, ~1.6 m/s) to conditions beyond a violent storm (Beaufort 11, ~30–32 m/s). South Africa's structural loading code SANS 10160-3 specifies peak gust design speeds of approximately 36–48 m/s in coastal Terrain Category 2 — the FST201's 50 m/s ceiling comfortably covers structural monitoring and safety shutdown requirements across all local exposure categories.

Can the FST201 and FST202 be used together as a complete wind monitoring station?

Yes — this is the recommended configuration. Both sensors share the same 12–30 VDC supply and output independent 4–20 mA signals, so they wire to two separate analogue input channels on the same PLC or data logger. No additional signal isolators, power supplies, or protocol converters are needed. The result is a compact, two-sensor station that delivers wind speed and direction in real time — the minimum dataset required by most South African site safety, meteorological, and environmental monitoring standards.

Do FST wind sensors work in freezing or sub-zero conditions?

Yes. The FST201 includes an internal heater that activates automatically when ambient temperature drops below 0°C, preventing ice from forming on the rotating cups and causing false-zero readings. Both the FST201 and FST202 also incorporate automatic temperature compensation to maintain measurement accuracy across a wide ambient temperature range. For South African Highveld sites at 1,500–1,800 m elevation — where winter nights regularly drop below 0°C — the FST201's built-in heater provides a significant operational advantage over unheated anemometers.