Timekeeping - Campbell CR300 Series Product Manual

NANs are expected in the following conditions:
Input signals exceed the voltage range chosen for the measurement.
l
An invalid SDI-12 command is sent
l
An SDI-12 sensor does not respond or aborts without sending data
l
Undefined arithmetic expressions, such as 0 ÷ 0.
l
NAN is a constant that can be used in expressions. This is shown in the following code snip that
sets a CRBasic variable to False when the wind direction is NAN:
If WindDir = NAN
WDFlag = False
Else
WDFlag = True
EndIf
If an output processing instruction encounters a NAN in the values being processed, NAN will be
stored. For example, if one measurement in a data storage interval results in NAN, then the
average, maximum and minimum will record NAN.
NOTE:
There is no such thing as NAN for integers. Values that are converted from float to integer
will be expressed in data tables as the most negative number for a given data type. For
example, the most negative number of data type FP2 is –7999; so, NAN for FP2 data will
appear in a data table as –7999. If the data type is Long, NAN will appear in the data table as
–2,147,483,648.
Because NAN is a constant, it can be used in conjunction with the disable variable parameter
(DisableVar) in output processing instructions. Use variable = NAN in the DisableVar
parameter to discard NANs from affecting the other good values.

17.3 Timekeeping

Measurement of time is an essential data logger function. Time measurement with the onboard
clock enables the data logger to run on a precise interval, attach time stamps to data, measure
the interval between events, and time the initiation of control functions. Details on clock
accuracy and resolution are available in the
battery backs the clock when the data logger is not externally powered (see
109)).
Then
System specifications (p. 183). An internal lithium
Internal battery
17. Tips and troubleshooting
(p.
121