VTI Instruments EX1629 - Vtex1629_Measure_Unstrained_Voltage

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EX1629 Command Set 207
vtex1629_measure_unstrained_voltage
FUNCTION PROTOTYPE
ViStatus vtex1629_measure_unstrained_voltage (ViSession vi, ViInt32 _VI_FAR channels[],ViInt32
numberOfChannels, ViInt32 sampleCount, ViReal64 _VI_FAR measuredValues[], ViPInt32
numMeasuredValues, ViBoolean setEuconv);
FUNCTION PARAMETERS
vi = contains a session handle to the instrument. This handle is obtained by the function and remains valid until the
session is closed.
channels = an input integer array containing a list of channel numbers for which the unstrained voltage will be
measured. Valid input values: 0 to 47.
numberOfChannels = the size of the channels list. Valid input values: 1 to 48.
sampleCount = an integer input value that indicates the number of samples to average. See the Description section
below for valid input values.
measuredValues = a real return array of the measured values. The measured values are placed in the array
according to the channels array passed to the function. In other words, for every channel number in channels, there
will be a corresponding unstrained voltage measurement in measuredValues.
numMeasuredValues = an integer return value that indicates the number of measured samples actually returned in
the measuredValues array.
setEuconv = a Boolean input value indicating whether the measured values will be used for future EU conversions.
DATA ITEM RESET VALUE
Not applicable to this function.
DESCRIPTION
This function measures the unstrained voltage for a particular list of channels. The unstrained voltage is one of the
variables in the strain EU conversion functions (see the Basic Operation section). A precise reading of the
unstrained voltage is necessary for accurate strain gage measurements. The measured values are returned in the user-
provided measuredValues array. Setting the setEuconv parameter to VI_TRUE (1) indicates that these values are
to be used for future EU conversions. Setting it to VI_FALSE (0) causes this data to be discarded after being read.
Using VI_TRUE is a short cut that eliminates the need for invoking vtex1629_set_unstrained_voltage for each
channel.
The sampleCount parameter typically can be set to values between 1 and approximately 9000 samples if sampling
is performed at 500 Hz and filtering turned off. Since the maximum number of samples that can be stored is
dependent on available memory and other settings this value can vary. If filters are turned on and/or sampling
frequency is reduced, for example, this would decreases the maximum value.
EXAMPLE
ViSession instrumentHandle;
ViInt32 channels[5] = {0, 1, 2, 3, 4};
ViInt32 numberOfChannels = 5, numValues = 0;
ViReal64 data[5];
ViStatus status;
…
status = vtex1629_measure_unstrained_voltage( instrumentHandle,
channels,
numberOfChannels,
100,
data,
&numValues,
VI_TRUE );