Section 2
Functional Description
9
FT742-SM (RS422 & RS485) Sensors
– User Manual
2 FUNCTIONAL DESCRIPTION
2.1 Technical Performance
Sensor Performance
1 & 2
Measurement Principle
Acoustic Resonance (compensated against variations in temperature,
pressure and humidity)
Wind Speed Measurement
Range
0-75m/s
Resolution
0.1m/s
Accuracy
±0.3m/s (0-16m/s)
±2% (16m/s-40m/s)
±4% (40m/s-75m/s)
Wind Direction Measurement
Range
0 to 360°
Sensor Accuracy
4
RMS
Compass Accuracy
5
RMS
Resolution
1
Environment
Temperature Range
-40 to +85
C (operating and storage)
Humidity
0-100%
Altitude
0-4000m
Data I/O
Interface
RS422 (full-duplex) or RS485 (half-duplex). The communications
interface option is programmed at the factory.
Format
ASCII, polled or Continuous Update modes (CU on RS422 only)
Data Update Rate
Up to 10 measurements per second (10Hz)
Power Requirements
3, 4 & 5
Supply Voltage
24VDC nominal (6-30VDC range). A minimum of 9VDC is required
for heater operation
Sensor Current (Heater off)
25mA nominal (29mA with compass enabled)
Heater Current (Heater on)
6
Up to 2A + nominal
Physical
Weight
252g
Material
Aluminium alloy (external body hard anodised)
I/O Connector
8-way M12 connector
Mounting Method
Surface-Mount with compressed O-ring/screw fit
Notes:
1. All specifications subject to change without notice.
2. Specifications calculated with the default settings and filters enabled.
3. See safety instruction requirements (page 5 and 6).
4. The heater set-point temperature can be configured by the user. Modifications to the heater current
limit and under-voltage limit are not permitted on the FT742-SM range, for further details contact FT
Technologies.
5. The current draw from the heater will depend on the environmental cooling and the temperature
setpoint. The sensor is limited to 2A
4
nominal by default. The maximum power is 60W (30V & 2A).
6. A suitable PSU capable of providing up to 2.5A maximum is recommended.
