SONIC ANEMOMETER SET-UP
AND COMMUNICATION
The sonic anemometer uses SDI-12 communication protocols. This method allows for communication with the sonic via a terminal or terminal emulator. Configuration changes and checks can be accomplished using LoggerNets terminal emulator. The sonic anemometers are also addressable so that numerous sonics can be connected to a single datalogger. There are also many commands that can be used but only the most common are listed below, see pages 53 – 66 of the WS425 manual for a complete list of commands.
Communication settings are as follows:
1200 baud, 1 start bit, 7 data bits, Even parity, 1 stop bit.
The current address of the sonic anemometer is 0. All commands to the sonic will need a leading 0 in order for the sonic to recognize the commands.
The sonic anemometer has 5 wires. Two of the wires are for power, one is for signal and the remaining two are for ground. See table below or the wiring diagram on page 23.
COLOR
/USE
/LOCATION
BLK / 12VDC GND / POWER SUPPLY 2BRN / 12VDC POWER / POWER SUPPLY 2
GRN / 36VDC HEATER GND / POWER SUPPLY 1
GRY/PNK / 36VDC HEATER POWER / POWER SUPPLY 1
WHT/YLO / SIGNAL / CR23X C5
In order to communicate with the sonic anemometer the terminal emulator in LoggerNet will have to be started. If the menu bar is not visible or minimized LoggerNet is not running and it will have to be started (start button, programs, LoggerNet).
Once LoggerNet is running the Terminal Emulator will need to be started. It is located under the “Test” menu option.
When the Terminal Emulator screen is up, select the device from the bottom left hand drop down menu. Choose MetTower as this is the system that the sonic anemometer is connected to. Next click on “Open Terminal” button. The red warning in the upper left hand corner should change from Not Active and red to MetTower and green.
In order to get the attention of the sonic anemometer and to let the CR23X know that communication with the sonic is required, type 5X. The “5” stands for the control port to which the sonic is attached.
The following are common commands used to configure and check the sonic anemometer:
TypeUsageReturned
?!Address Querya = sensor address
aX*!Check Measurement Unitax
a = addressx = 0(mph), 1(kt),
2(Km/h), 3(m/s)
aXUx!Change Measurement Unitnone
a = address
XU = change unit command
x = 0(mph), 1(kt), 2(Km/h), 3(m/s)
TypeUsageReturned
XAb!Change Addressb!
a = address
A = change address command
b = address to change to
aXHx!Heater Control Commandax
a = address
XH = heater command
x = 0(disable heater), 1(enable heater)
aM0!Measurement Commandsee below
The measurement values that have been selected are as follows:
a<WS<WD<x<y<s>
a = address of sonic anemometer
WS = Polar wind speed in selected units
WD = Polar wind direction
x = x component of WS in selected units
y = y component of WS in selected units
s = static speed of sound in mph
Once communications with the sonic anemometer are no longer needed, click on the “Close” button or the “X” button in the upper right hand corner.
**Note: The timeout for communications is small; therefore, it will be necessary to type 5X to open communications more than once. The emulator program will inform the user when communications are open (entering SDI-12) and when they are closed (exiting SDI-12).