Wind speed output, Frequency – Vaisala WMT700 User Manual
Page 37
Chapter 4 _______________________________ Operating WMT700 in WS425 Analog Output Mode
VAISALA _______________________________________________________________________ 35
Wind Speed Output
In a system configured for WS425, you can set WMT700 to measure
wind speed and send analog output as frequency or voltage.
The sections below describe WMT700 analog output when:
- Settings are configured according to Table 10 on page 34.
- Wires are connected according to section ROSA Cable 10m (Analog
Frequency
When frequency is selected as the wind speed analog output, WMT700
sends a pulsed signal of 0 to 10 V with a frequency proportional to wind
speed through AOUT1. Every mile per hour adds 5 Hz (WS425) or every
meter per second adds 10Hz (WMT700) to the frequency. In SI units, a
change of 0.894 meters per second adds 10 Hz to the frequency. A
frequency counter is required to count the output in Hz and the
calculation that scales the result to appropriate units.
Figure 10 on page 36 shows the frequency output when an adapter cable
for analog frequency output and a WS425 cable are used. With
WMT700, the wind speed signal appears at pin 13.