Campbell Scientific WINDSONIC 2-D Sonic Wind Sensors - Manual (Page 20)

WindSonic Two-Dimensional Sonic Anemometer
7.2.3 SDI-12 Wiring
The WindSonic4 interfaces to a Campbell Scientific datalogger using SDI-12.
SDI-12 is a three-wire interface used between processor-based sensors and
digital recorders (TABLE 7-4). Each SDI-12 sensor has a unique address. The
factory-set address for the WindSonic is 0. To change the SDI-12 address, see
Section 7.5, Changing the SDI-12 Address Using LoggerNet and a Datalogger,
for wiring and programming. At a 1 Hz measurement rate, a maximum of 4
WindSonic4s can be measured by a datalogger.
TABLE 7-4. WindSonic4 to Datalogger Connections
Description Color Datalogger
SDI-12 data Green SDI-12 Input or Control Port
SDI-12 power Red 12 Vdc
SDI-12 reference Black G
Shield Clear G
7.3 Datalogger Programming for RS-232 Output
The WindSonic1 updates the RS-232 output to a user-set frequency. The
CRBasic dataloggers (CR800-series, CR1000, and CR3000) use the
SerialInRecord() instruction to retrieve the latest record sent by the
WindSonic1 at the scan interval. This ensures that the most current wind data
is available for use by the program.
The datalogger and WindSonic1 each use their own internal clocks. These
clocks are not perfectly synchronized with each other and will drift in and out
of phase. This phase drift could cause missed samples because no new data
was transmitted to the datalogger in time for the next scan. The programs in
this manual record the number of missed records as no new data (nnd_TOT).
A no new data error will occur if the WindSonic is disconnected from the serial
port, the WindSonic has no power, or the datalogger and WindSonic clocks
have drifted out of phase by one cycle.
Early versions of the datalogger operating system (OS) did not support serial
communication using control ports or the instruction SerialInRecord(). It may
be necessary to update the datalogger OS. TABLE 7-5 lists the OS versions
that support both serial communications using control ports and the
SerialInRecord(). The most current datalogger operating systems are
available on the Campbell Scientific website in the Support|Downloads section.
12