Rotorvane for Windows
Reads a Rotorvane anemometer either directly connected to the computer serial
port or connected via modem.
Displays the wind speed and direction and (optionally) logs the wind data
to disk.
Rotorvane for Windows
installation
package
(Select a calibration speed of 20 m/s)
Serial port software considerations
Rotorvane F has two serial ports.
OUT1 only sends data when so requested by the host. If the host sends an
ASCII a then the anemometer returns the wind speed (1 bit = .2 m/s). If the
host sends an ASCII b then the anemometer returns the wind direction (1 bit
= 1/256 circle).
Qbasic example
OUT2 continuously delivers wind data in the form
ASCII s, ASCII d, speed (1 bit = .2 m/s), dir'n (1 bit = 1/256 circle)
Serial port drivers should include automatic recovery from comms errors and
unplanned depowering and repowering.
Analog port software considerations
Simple analog output of wind direction is unavoidably subject to occasional errors. When the wind direction changes from 359 degrees to 0 degrees, the analog output voltage swings from 10 volts to 0 volts. This change requires a brief but finite time. If the external equipment reads the analog port voltage during this change then the reading is wrong. There is a similar potential for error when the wind direction changes from 0 to 359 degrees.
Most bad data can be rejected by reading direction twice in sucession. Use 0.1 second intervals between the reads and discard the results if the difference exceeds 90 degrees. If occassional gross errors in wind direction measurement can not be tolerated then a serial interface is a better choice.