Section 18. Troubleshooting
153
18.1.2 NAN and ±INF
NAN (not-a-number) and ±INF (infinite) are data words indicating an
exceptional occurrence in CR200(X) function or processing. NAN is a constant
that can be used in expressions such as in CRBASIC EXAMPLE. Using NAN in
Expressions (p. 153) NAN can also be used in the disable variable (DisableVar)
i
n output processing (data storage) instructions, as indicated in CRBASIC
EXAMPLE. Using NAN in Expressions p. 153.
CRBASIC EXAMPLE 21. Using NAN in Expressions
If WindDir = NAN Then
WDFlag = True
Else
WDFlag=False
EndIf
18.1.2.1 Measurements and NAN
A NAN indicates an invalid measurement.
18.1.2.1.1 Voltage Measurements
The CR200(X) measures voltage inputs ranging from 0 to 2500 mV. Input
signals that exceed this ranges result in an over range indicated by a NAN for
the measured result. A voltage input not connected to a sensor is floating and
the resulting measured voltage often remains near the voltage of the previous
measurement. Floating measurements tend to wander in time, and could
temporarily impersonate a valid measurement.
18.1.2.1.2 SDI-12 Measurements
SDI-12 Measurements
NAN is loaded into the first SDI12Recorder () variable under these conditions:
• When busy with terminal commands.
• When the command is an invalid command.
• When the sensor aborts with CR LF and there is no data.
18.1.2.2 Floating Point Math, NAN, and ±INF
TABLE. Math Expressions and CRBASIC Results (p. 154) lists math
expressions, their CRBASIC form, and IEEE floating point math result for the
CR200(X).
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