Measurement Computing UL for NI LabVIEW - Manual (Page 9)

Overview of the Universal Library VIs Signal conditioning VIs
OptAIn.VI – Specifies analog input options.
Both AInScBg.VI and AInScFg.VI have an input called options which should be wired to this VIs output. It
generates a value based on the Anded values of its inputs.
SetTrig.VI - Set the trigger source.
Configures the type and threshold value of external trigger signals.
TIn.VI - Single temperature input
Reads a temperature input channel and, as necessary, filters it, performs cold junction compensation, and
linearization.
TInScan.VI - Scans a range of thermocouple inputs.
Reads the temperature from a range of channels as described above. Returns the temperature values to an
array.
Signal conditioning VIs
ACvtData.VI - Converts analog data
Each raw sample from an analog input is a 16-bit value. On some 12-bit A/D boards it consists of a 12-bit
A/D value along with a four bit channel number. On 16-bit A/D boards it contains the 16-bit A/D value.
This conversion is done automatically by the AIn VI. It can also be done automatically by the AInScBg.VI or
the AInScFg.VI with the
CONVERTDATA option. In some cases though, it may be useful or necessary to collect
the data and then do the conversion sometime later. The ACvtData.VI takes a buffer full of unconverted data
and converts it.
ACnvPrDt.VI - Convert pre-trigger data
When data is collected by either APretrBg.VI or APretrFg.VI, the same conversion needs to be done as
described above for ACvtData.VI.
However, both APretrBg.VI and APretrFg.VI collect analog data into an array. They treat the array like a
circular buffer. While they are waiting for the trigger to occur, they fill the buffer. When the end of the buffer
is reached, they return to the beginning of the buffer. When the trigger signal occurs, the VIs continue
collecting data into the circular buffer until the requested number of samples have been collected.
When the data acquisition is complete, all of the data is in the array, but it is in the wrong order. The first
element of the array does not contain the first data point. The data has to be rotated to the correct order.
This conversion can be done automatically by the APretrBg.VI or APretrFg.VI with the CONVERTDATA option.
In some cases, though, it may be useful or necessary to collect the data and then do the conversion sometime
later. The ACnvPrDt.VI takes a buffer full of unconverted data and converts it.
ACalData.VI - Calibrates raw data.
Calibrates raw data collected by cbAInScan() when the real-time software calibration is turned off.
FromEng.VI - Convert to raw data.
Converts one data sample or an array of data samples from engineering units to raw data format. Can also
convert a single voltage (or current) to a D/A count value for use as an analog trigger threshold value.
ToEng.VI - Convert to engineering units.
Converts one data sample or an array of data samples from raw data format to engineering units.
ScalePnt.VI - Converts a raw data point to engineering units.
ScaleArray.VI - Converts raw data in an array to engineering units data in an array.
9