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
Acoustic Temperature Measurement
Units
Celsius, Fahrenheit or Kelvin
Resolution
0.1°
Accuracy
±2°C under the following conditions:
Wind speed between 5m/s and 60m/s
Temperature Difference < 10°C (Sensor Temp. vs Air Temp.)
Operating (air) temperature between -20°C and +60°C
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 mode using RS485HD requires software V7.4+)
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.
