Decagon Devices VP-3 Operator's Manual page 20

VP-3 6 COMMUNICATION
The SDI-12 communication protocol is supported by Campbell Sci-
entific data loggers like the CR10X, CR200, CR1000, CR3000, etc.
Direct SDI-12 communication is supported in the Terminal Emulator
mode under the "Tools" menu on the Connect screen. Detailed in-
formation on setting the address using CSI data loggers can be found
on our website at http://www.decagon.com/support/downloads.
Power
The VP-3 is an extremely low power sensor. When continuously
powered, but not making a measurement or communicating, it uses
30µA. When using the sensor as part of an SDI-12 bus, it is recom-
mended that the sensors be excited continuously to avoid issues with
initial sensor startup interfering with the SDI-12 communications.
Reading
When reading the VP-3 in SDI-12 mode, the first number output
by the sensor is vapor pressure in kPa, the second number is temper-
ature in Celsius, and the third number relative humidity in a unitless
ratio from 0 to 1 (0 to 100%).
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