User's Guide _______________________________________________________________________
108___________________________________________________________________ M210543EN-B
Electrical Specifications
Table 21
PWD22 Electrical Specifications
Property
Description / Value
Maximum power
consumption
6 W, 12-50 VDC
Optional luminance sensor: 2 W, 24 V
Optional hood heaters: 65 W, 24 V
Sensor electronics
Lock-in amplifier.
LED power stabilizer.
Contamination monitor.
Lens heater.
Temperature sensor.
Outputs
Serial data line may be used either as RS-232 or
RS-485 (2-wire) level signals.
Three relay controls (open collector).
Analog output
8-m power/data cable standard. The PWD22 end is
equipped with connector.
Output data
Automatic or polled data messages.
Visibility, present weather, precipitation, and status
data.
Automatic message type and interval is selectable
at 15 s ... n x 15 s (n < 18) intervals.
Auxiliary data
Low visibility alarms in the data messages. Three
adjustable alarm limits to set the three relay
controls.
Hardware status (fail/warning) in the data
messages. Third relay output can also be driven by
hardware status.
Optical Specifications
The operating principle of the device is to measure forward scatter at
an angle of 45
°
.
Table 22
Optical Specifications of the Light Transmitter
Property
Description / Value
Light source
Near-infrared Light Emitting Diode
Peak wavelength
875 nm
Reference photodiode For light source control
Backscatter
photodiode
For contamination and blockage measurement
Eye safety
Eye safe in accordance with International Standard
IEC/EN 60 825-1; edition 1.2