Young Ultrasonic Anemometer Voltage and Serial Output Model 81000 - Manual (Page 6)

Page 5
81000-90
m/s 0.01 C° 0.01
mph 0.1 F° 0.01
km/h 0.1 C° 0.01
knots 0.1 F° 0.01
UNITS 2
-------------------
1) cm/s
2) m/s
3) mph
4) km/h
5) knots
X) EXIT TO MAIN MENU
6.10 VOLTAGE OUTPUT FORMAT
VOLTAGE OUTPUT FORMAT sets format, scaling and output
range for voltage outputs. Only wind speed scaling may be set by
the user. AZIMUTH, ELEVATION, and SONIC TEMPERATURE
scaling is xed. Full scale output range for all voltage outputs may
be set to either 0-4000 or 0-5000 millivolts.
Choose format from the menu.
VOLTAGE OUTPUT FORMAT 2
------------------------
1) U V W TEMP
2) SPEED AZ ELEV TEMP
X) EXIT
6.10.1 SCALING
If UVW format is chosen, the following prompt is shown with cur-
rent wind scale setting:
VOLTAGE OUTPUT SCALE: -25 TO 25 m/s
ENTER NEW VALUE (10-60):
You must enter a value for the scale. Note that with UVW format,
the value you enter will be bipolar scale (ie: 25 means -25 to +25
m/s).
If SPEED AZIMUTH ELEVATION format is selected, the following
prompt is shown with current wind scale setting:
VOLTAGE OUTPUT SCALE: 0 TO 50 m/s
ENTER NEW VALUE (10-60):
You must enter a value for the scale.
With SPEED AZIMUTH ELEVATION format, AZIMUTH scale is
xed at 0 to 540° and ELEVATION is xed at -60° to +60°.
SONIC TEMPERATURE scale is always 220 °K to 320°K.
6.10.2 RANGE
After setting the scale, the current setting for output range is
shown along with a menu for changing it.
VOLTAGE OUTPUT FULL SCALE = 5
-----------------------------
4) 4000 mV
5) 5000 mV
X) EXIT
The 5000 millivolt (mV) output range (default) is recommended for
all new installations. The 4000 mV range is compatible with earlier
models.
6.10.3 CONVERSION TO ENGINEERING UNITS
The range applies to all voltage output channels. The following
relationships may be used to interpret output values:
For UVW format:
U,V, or W windspeed = [(Scale x 2 / Range) x mV] - Scale
Example:
W channel output value = 2550 mV
Scale = 25 m/s
Range = 5000 mV
SPEED = [(25 x 2 / 5000) x 2550] -25 = 0.5 m/s
For SPEED AZIMUTH ELEVATION Format:
Windspeed = [(Scale / Range) x mV]
Example:
SPEED channel output value = 1950 mV
Scale = 25 m/s
Range = 5000 mV
Speed = [(25 / 5000) x 1950] = 9.75 m/s
Azimuth = [(540 / Range) x mV]
Example:
AZIMUTH channel output value = 4250 mV
Range = 5000 mV
Azimuth = [(540 / 5000) x 4250] = 459
°
If the result is greater that 360, subtract 360.
Azimuth = (459 - 360) = 99°
Elevation Angle = [(120 / Range) x mV] -60
Example:
ELEVATION channel output value = 2200 mV
Range = 5000 mV
Elevation Angle = [(120 / 5000) x 2200] - 60 = -7.2
°
Voltage output scale for sonic temperature depends only on the
temperature voltage output value and selected range.
Temperature = [(100 / Range) x mV] +220
Example:
TEMPERATURE channel output value = 3780 mV
Range = 5000 mV
Temp
° K = [(100 / 5000) x 3780] +220 = 295.6 °K
To convert to °C, subtract 273.15.
295.6 - 273.15 = 22.45 °C
When ERROR HANDLING is set to INCLUDE INVALID DATA, the
voltage output channels go to positive full scale when an invalid
measurement occurs. When set to OMIT INVALID DATA, the
voltage output remains at the last valid value until a new valid
measurement occurs.
IMPORTANT:
For VOLTAGE OUTPUTS to function properly, the 81000 serial
output must be set to CUSTOM format.
6.11 WAKE CORRECTIONS
WAKE CORRECTION enables or disables real-time correction
algorithms. To compensate for ow distortions in the wake of sup-
port struts and other mechanical features, each 81000 is individu-
ally calibrated in the YOUNG factory wind tunnel (NIST traceable)
to generate a unique correction table which is stored in the unit.
Additional compensating algorithms correct for elevation angle
distortions and crosswind effects on speed of sound.
WAKE CORRECTION: YES
USE WAKE CORRECTION? (Y/N):
7.0 APPLICATION NOTES
SERIAL COMMUNICATION
Selection of RS232 or RS485 is made inside the sensor j-box
by positioning the shorting blocks on jumper W6. Typical wiring
connections are shown in APPENDIX A. RS-485 half-duplex
connections can simplify some installations since less cable is