Designing a Biosignal Logger Part 1: Acquiring a Biosignal (Biomedical Toolkit)

In Part 1 of this tutorial, you design a VI to acquire a biosignal from a DAQ device and then view the acquired biosignal.

What to Use

Use the following objects to acquire and view a biosignal:

Biosignal Acquisition Express VI		Convert from Dynamic Data Express VI		Waveform Graph		While Loop
Add		Add		Add		Add

What to Do

Create the following block diagram to acquire and view a biosignal.

The following list describes important details about the previous diagram:

	Use the Biosignal Acquisition Express VI to acquire a biosignal from the DAQ device. When you add this Express VI to the block diagram, the Configure Biosignal Acquisition dialog box appears. Complete the following steps to configure the Biosignal Acquisition Express VI: Select your DAQ device from the Device name pull-down menu. Select the channel that you want to utilize from the Physical channel pull-down menu. Enter a unique name for the channel in the Name text box. Set the maximum and minimum input values of the channel in the Input Range section. Click the Add as New Channel button to add the channel. Click OK to apply the current configuration and close the dialog box.
	Use the Convert from Dynamic Data Express VI to convert the acquired biosignal data into waveform type. Because you are logging a single data channel, select Single waveform from the Resulting data type listbox in the Configure Convert from Dynamic Data dialog box. Note  You need to convert the data into waveform type before displaying the data on a waveform graph or preprocessing the data.
	Add a waveform graph to the front panel to display the acquired biosignal. Give the graph a unique name, such as Original Biosignal.
	Use a While Loop to continuously acquire the biosignal. Right-click the conditional terminal and select Create Control from the shortcut menu to create a stop Boolean control. Also wire the output of the Boolean control to the stop? input of the Biosignal Acquisition Express VI to ensure that the Express VI stops acquiring data when you stop the biosignal logger.

After you complete this part of the tutorial, you can run the VI to acquire a biosignal from a DAQ device and then view the acquired biosignal.

Caveats and Recommendations

• You can increase the Sampling rate in the Configure Biosignal Acquisition dialog box to take more samples per second or decrease the Sampling rate to take fewer samples per second. A higher sampling rate provides better resolution but may impact performance.
• You can increase the Block size in the Configure Biosignal Acquisition dialog box to increase the number of samples acquired per block or decrease the Block size to decrease the number of samples acquired per block. A bigger block size reduces the number of blocks necessary to write to the file. A smaller block size provides for faster data updating if you perform real-time analysis.

Examples

Refer to labview\examples\Biomedical\Tutorials\Designing a Biosignal Logger.lvproj for a completed version of the VI you create in this part of the tutorial.