SpectrumDAQ User Instructions

Submitted by pdebeule on Sat, 05/21/2011 - 12:02

User Instructions

Try it out…

You can start a data acquisition (DAQ) run in SpecLAB either by

  • Choosing DAQ>>Run from the menu options
  • Pressing Control+r
  • Clicking the button with the green arrow located on the toolbar

First, you will be presented with a screen which asks for an experimental description (EXP) and your
name (MYNAME). Additionally, you can add a comment as a note. After clicking OK, a data acquisition
will start and some objects on the front screen are greyed-out.

Similarly, you can stop a DAQ run by

  • Choosing DAQ>>Stop from the menu options
  • Press Control+s
  • Clicking the button with the red square located on the toolbar

SpecLAB will generate a random spectrum every second on average during a DAQ run, as well as 3 parameters (a string, integer and floating point
number). All this data is stored in a TDMS data streaming file which is located in your default LabVIEW data directory - under Windows this
is normally C:\My Documents\LabVIEW Data. The actual file name is determined as follows:

MYNAME_DATE_EXP.tdms

Alongside with the binary TDMS data file, a TDMS_INDEX file is created with the same name, which describes, in XML, how the data in the TDMS file
is organised. Both files need to be retained in the same directory in order to open the TDMS data file successfully afterwards.

When you start another DAQ run and specify the same experimental description and name, SpecLAB will store the newly generated data in the same TDMS file, but as a new DAQ run. This is indicated by the automatic increment of the Run number, which is located on the top left hand corner. In case you specify another experimental description or name, SpecLAB will simply store the new DAQ run in a new file named accordingly.

 

Navigating through a recorded data set…

After recording a DAQ run, there are several options to browse through the acquired data. The spectrum shown in the top graph is indexed by the Spectrum Number, which can be changed as follows:

  • Enter a new Spectrum Number directly or move the Spectrum Number Slide
  • Use the left and right keyboard arrows to decrement and increment the Spectrum Number respectively
  • Move the green cursor on the bottom graph

The DAQ run which is displayed at any point in time is identified by the Run Number on the top left hand corner. By changing this number, you can load a new data set in memory, display and analyze it. You can change the Run Number by:

  • Enter a new Run Number directly
  • Use the up and down keyboard arrows to decrement and increment the Spectrum Number respectively.

Please note that it is impossible to enter invalid Spectrum Numbers or Run Numbers. The minimal value is always 1, while the maximum number is determined by the DAQ run or DAQ file respectively.

Last but not least, it is also possible to change the DAQ file from which data is displayed. This can be done by:

  • Opening a new data file by choosing the menu option File>>Open, pressing Ctrl+o or clicking the button with the folder icon on the toolbar
  • Looking at a different data file which was previously opened or used for DAQ. This can be done by choosing the desired data file from the View
    menu option

 

Visualising and analysing your data set…

Single spectra of a single DAQ run are displayed in the top graph of the Data tab. The bottom graph of the same tab represents the history of two spectral data points over the course of the currently displayed DAQ run, which are indicated by the yellow and red cursors on the top graph.

 

For the LabVIEW programmers…

How do I quickly customize SpecLAB to do what I want?

In the hardware subdirectory of the modules directory there is a LabVIEW detector.lvclass file which represents the LabVIEW Object Oriented Programming (LVOOP) class that controls the spectral detector. The following LabVIEW virtual instruments (VI’s) are implemented in SpecLAB to SIMULATE a detector:

  • Detector.lvclass:Constructor.vi
    Initialisation of the spectral detector and allocation of software recourses to variables registered by Detector.ctl.
  • Detector.lvclass:Destructor.vi
    Shutdown of the spectral detector and release of software resourses allocated to the detector.
  • Detector.lvclass:Get Spectrum.vi
    Fetch the latest available spectrum.
  • Detector.lvclass:New Spectrum Availability.vi
    Check if a new spectrum is available.
  • Detector.lvclass:Get Parameter List.vi
    Fetch the parameters associated with the last spectral data acquistion.
  • Detector.lvclass:Set Parameter.vi (OPTIONAL)
    In case your spectral detector has software programmable parameters, this function can be used to alter them.

Replace these functions with your own to record spectra with SpecLAB with your spectral instrument of choice.

Tags: