Section 6
Parameter Settings
60
FT742-SM (RS422 & RS485) Sensors
– User Manual
7.4.26 WV Polar: Query the Wind Velocity Reading
Command
Parameter
WV (Polar)
Command
Syntax
SET Sensor:
N/A
QUERY Sensor:
$<listenerID>,WV?*<checksum><cr><lf>
$aa,WV?*hh<cr><lf>
Sensor output:
$<talkerID>,WVP=<speed>,<angle>,<status>*<checksum>
<cr><lf>
$aa,WVP=xxx.x,xxx,x*hh<cr><lf>
Parameters
<speed>
000.0 to 075.0
Measured wind speed in metres per second
<angle>
000 to 359
Measured wind direction in degrees relative to sensor datum
< status >
0 to Z
Indicates whether an error condition was detected by the sensor
operating system. A status value of 0 indicates no issues have been
detected (ASCII 30(HEX)).
If the sensor detects an error condition, the status character will be
set to 1. If the Overspeed Warning Scheme (see Section 2.8) is
enabled and if the sensor detects wind speed above the maximum
range, the status flag will be set to 2.
Examples
Example 1
The following example illustrates the polar wind velocity data format. The example shows
the sensor output with a wind speed of 20m/s and a wind angle of 45°.
Message
Comment
$01,WV?*//<cr><lf>
Query the wind velocity
$WI,WVP=020.0,045,0*73<cr><lf>
Sensor polar response
Description
The WV command returns the wind velocity value in the currently selected format. Polar or
NMEA formats are available. Use the DF command, Section 7.4.4, to select
the required
output format.
Polar Format: The sensor returns the magnitude of the wind speed (m/s) and the wind
direction (0-359°).
NMEA 0183 Format: The sensor returns the NMEA 0183 Wind Speed and Angle sentence
MWV (see WV NMEA, Section 7.4.27).
It is important that the status is always monitored. Readings associated
with errors should not be treated as valid. It is important that the host
computer is able to cope with occasional periods when valid data may
be temporarily unavailable.
The status is cleared once the WV command is executed, provided that
the error condition does not persist.
