Data in Labview can be exported to an lvm (similar to a .csv) file, which contains a header and comma or tab seperated columns of data.

1. To get started, set up the DAQ and choose your sample time appropriately. Keep in mind that faster sampling rates will produce a lot more data and introduce additional noise.

2. Once your VI is setup, add the Write To Measurement File block that records signals to an .lvm file. You can find it in the function palette: Programming >> File I/O >> Write To Measurement File. Then, connect the time-domain signal coming out of the DAQ block to the Write To Measurement File block. Don't worry about filtering or processing right now, because you can always do this later in MATLAB.

3. Right-click on the Write To Measurement File block, and click Properties. This will bring up a window to configure the block. Choose the following settings:

   • File Format = Text (LVM)
   • Segment Headers = One header only
   • X Value (Time) Columns = One column per channel
   • Delimiter = Comma And choose a filename ending in .lvm to save your data into, and then click OK to close the configuration menu.

4. Start recording by clicking Run or Run Continuously. To stop, press Stop. Data will be recorded to the specified file for as long as your VI is running. Be careful about overwriting previously recorded data by pressing Run twice. You should set a new filename or rename the first one to prevent data loss.

5. Move lvmread.m to the directory where you saved your .lvm file (or visa versa). Now, open MATLAB and change to that same directory by typing: cd directory/with/mydata.lvm, replacing the path with the directory where you saved your data to.

6. Read the data into the variable data by typing: data = lvmread('my_measurement_file.lvm'). Each signal is recorded into columns with a paired time column preceding it. For example, an .lvm file with only one signal recorded will have two columns of data, where the first column x holds the time steps of 1/f_s, and the second column is y, which represents the discreted voltage measured at the different timesteps by the ADC.

You can access split the data into the x and y columns with: x = data(:,1); y = data(:,2), which saves column 1 of data into x, and column 2 of data into y. See notes below for plotting the data.

Using MATLAB, you can customize your plots in many different ways. This text will not delve very deeply into how to make MATLAB plots. Use the help docs (http://www.mathworks.com/help/matlab/ref/plot.html) and google for more info.

Here are a few useful commands for manipulating plots. Note that these commands affect the most recently opened figure. You can switch between figures with the figure(i) command, where i is the number of figure you want to siwtch to. Click Window in the menubar to see a list.

• title('My Title') - Sets the title of the plot
• xlabel('Time (sec)') - Sets the label of the x-axis
• ylabel('Voltage (V)') - Sets the label for the y-axis
• xlim([0 5]) - Sets the window range for the x-axis (from 0 to 5)
• ylim([-10 10]) - Sets the window range for the y-axis

• In the .lvm file after the header, the first value in each pair of columns is the sample time, and second is the measured value at that time. Each additional signal will add another pair of columns in this way.

• When saving MATLAB plots to files choose .png format for the best results. Note that the size of the window when you save it will be the same size as the image, so drag it larger to improve the quality.