Lab Exercise 2: Data Acquisition with NI LabVIEW

Transcription

1 Objective When you have completed this exercise, you will be able: To use the DAQ Assistant to acquire analog data measurements with NI LabVIEW To use Write to Measurement express VI to log real time data to a file using LabVIEW. To use Excel to analyze the data. 1. Open NI LabVIEW and press <Ctrl-N> to open a blank VI. 2. Press <Ctrl-T> to tile front panel and block diagram windows. 3. Pull up the Functions Palette by right-clicking on the white space on the LabVIEW block diagram window. 4. To Control the Application with a While Loop Select Express»Exec Control»While Loop Place the While Loop on the Block Diagram Move the cursor to the loop upper left corner, then click & hold left mouse button Move the mouse to the lower right corner, then release the left button Add a Loop Counter Display Robert W Harrison 2017 Page 1 04/07/17

2 5. Move your mouse over the Express»Input palette, and click the DAQ Assist Express VI. Click again on the white space of the LabVIEW block diagram to place the DAQ Assistant VI. Robert W Harrison 2017 Page 2 04/07/17

3 6. To configure a Voltage Measurement application after DAQ Assistant appears on screen: Select Acquire Signals - selects type of signal as input Select Analog Input - selects input type Select Voltage - selects type of analog input Select ai0 - adds first analog input physical channel Click Finish Robert W Harrison 2017 Page 3 04/07/17

4 7. To configure Analog Input Channel Set Acquisition Mode to Continuous Set Min = 0 and Max = 10 Set Samples to Read = 1k Set Rate (Hz) = 10k Set Display Type to Chart Deselect Auto Scale Y-Axis Set display Amplitude scale Min = 0, Max = 10 To test the Analog Input, select Run Click Stop and Close the test panel window. 8. Click OK to close the Express block configuration window to return to the LabVIEW block diagram Robert W Harrison 2017 Page 4 04/07/17

5 9. Right-click the data terminal output of the DAQ Assistant Express VI (the blue output arrow on the right side) and select Create»Graph Indicator. 10. Notice that a graph indicator is placed on the front panel. 11. The block diagram should now look like the figure below. The Loop Counter Display is in the lower left and the Stop Button is in the lower right. Robert W Harrison 2017 Page 5 04/07/17

6 12. Change the graph indicator to a meter. Select Modern»Numeric»Meter. The meter will now appear on the Front Panel instead of the graph. 13. Modify the meter indicator by right-clicking it and selecting Properties On the Appearance Tab change the label Meter to Volts On the Scale Tab set Min = 0, and Max = 10 Robert W Harrison 2017 Page 6 04/07/17

7 14. To perform analysis on your data, select Expres»Signal Analysis>Statistics Express VI and place it on your Block Diagram. 15. A properties window will appear. Make the following selections and click OK. Statistical Calculations: Arithmetic Mean Extreme Values: Maximum, Minimum Robert W Harrison 2017 Page 7 04/07/17

8 16. Connect the data output of the DAQ Assistant VI to the Signals input of the Statistics VI. Robert W Harrison 2017 Page 8 04/07/17

9 17. Right-click the Arithmetic Mean output of the Statistics VI and select Create»Numeric Indicator. This will create a numeric indicator on the front panel that will display the mean. Repeat this step for both the Maximum and Minimum outputs of the Statistics VI. Your block diagram should resemble the following. Robert W Harrison 2017 Page 9 04/07/17

10 18. Right-click on the block diagram and select Express»Output»Write to Measurement File and place it inside the While Loop on the block diagram. Robert W Harrison 2017 Page 10 04/07/17

11 19. A configuration window will appear. Enter the following parameters and click OK. Note: Set "File Name" to your desired location 20. Wire the output of the DAQ Assistant Express VI to the input of the Write to Measurement File Express VI. Robert W Harrison 2017 Page 11 04/07/17

12 21. Your block diagram should now resemble the following figure 22. Save the vi in your file as exercise2.vi. 23. Connect the simulator box to the USB-6008/USB Run the vi. Change the voltage and observe the response ion the meter. 25. Click the Stop button on the Front Panel when finished. 26. Your file will be created in the folder specified. 27. Open the file using Microsoft Office Excel. Review the header and temperature data saved in the file. 28. Close the vi. Robert W Harrison 2017 Page 12 04/07/17