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CSAT3B Three-Dimensional Sonic Anemometer
16
FIGURE 5-10. CSAT3B power cable compensation plug
The primary indicator of low voltage is in the diagnostic flags returned by the
CSAT3B to the data logger. Flag number 32 (0x0020) indicates a low-voltage
condition was detected. If the instrument returns flag 32, first measure the
power source voltage and ensure that its DC value meets specifications. If that
value is appropriate, the voltage at the far end of the cable should be checked.
This must be tested under load so a splitter at the end of the cable will be
required to measure the terminal voltage. These two tests will eliminate the DC
voltage as the source of the problem. Any DC voltage below 12 V at the sensor
would be suspect for susceptibility to droop. In larger systems, even DC
voltages of 13-15 V can still experience enough droop to trigger the detection
under the right conditions. Power systems of 24 V are very unlikely to
experience enough droop to observe this problem. If the DC case checks out
but the flag is still observed, then the system would probably benefit from the
addition of a power compensation plug (FIGURE
).
Both splitters, pn 30293 and pn 30294, look similar; however, they
have a different number of pins and are not interchangeable.
FIGURE 5-11. CSAT3B CPI/RS-485 splitter
5.2.4.3 HUB-SDM8
The HUB-SDM8 (shown in FIGURE
) allows up to six SDM devices
(typically, one data logger and multiple SDM sensors) to be connected together
in parallel. In the case of the CSAT3B, up to five CSAT3Bs, or CSAT3B
daisy-chains using CSAT3BCBL1 cables, may be connected to the HUB-
SDM8. In cases where multiple CSAT3Bs are installed some distance from the
data logger, the HUB-SDM8 can be placed near the CSAT3Bs with a single
SDM cable extended from the hub to the data logger. This decreases the total
network cable length, which limits signal attenuation.
The HUB-SDM8 has eight terminal strips and features spring-loaded guillotine
terminals for easy wiring. It comes in a watertight enclosure and includes a U-
bolt for mounting to a vertical pipe or mast. An SDM Cable (CABLE5CBL-L;
NOTE