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540°
With the setting 0..540° uncontrolled jumping is avoid ed with unsteadiness (0°). Here the
unsteadiness is located at 540°. If the angle > 540°, a single jump to 180° takes place (540° -360° =
180).
Measured value output
Assigned wind direction
0°
West
90°
North
180°
East
270°
South
360°
West
450°
North
540°
East
Table 5: Assignment of wind direction with 0-540° angle range (as per VDI 3786 sheet 2)
When the calculated wind velocity is > 0,1 m/s, the wind direct ion reset.
The wind direction 0° is reserved for the calm.
When the wind velocities are > 0,1 m/s the exact wind direction north 0° is output respectively as
360 ° for differentiation to the calm.
Output value for this criterion is always the last-effective instantaneous value of the wind velocity.
720°
Another possible setting is scaling of 0..720°. As for 0.. 540° the unsteadiness is avoided at 360°. A
jump to 360° only takes place when the limit of 360° (> 720°) is exceeded for the second time.
It should be noted that an output of 0..720° the val ue 0° means a southerly wind.
See also Command AO.
7.3 Data acquisition
The main function of the ULTRASONIC firmware is data acquisition and preparation. For data
acquisition sound impulses are transmitted by the sensors in a clockwise direction and received by
the sensor opposite. The propagation time measured is a measure of the velocity. A measuring
cycle is complete when every sensor has performed transmit and receive once. The complete data
record is then time-stamped and passed on to the next level. After the plausibility check the
individual components are calculated and, depending on the setting, either output
(see 7.3.1) or written to the averaging buffer (see averaging) prepared and output.