Labview Exercises For Labview 7 - Michigan State University

e. The Debug Exercise (Main) VI Diagram window becomes active. Click on the StepOut button to complete the VI execution.LabVIEW also contains a probe to view the data as it flows through a wire.11. Enable the probe by selecting the Probe tool from the Tools palette and then clicking onany object.12. Single step through the VI again. (Remember: when the sub VI is executing, press theStep Over button in the sub VI diagram window.) The Probe windows should display thedata as it flows through that segment.13. LabVIEW can halt execution of a VI at any location on its diagram.14. Set breakpoints by selecting the Breakpoint tool from the Tools palette and clickinganywhere in the circuit.15. Run the VI by clicking on the Run button. The VI will pause at the breakpoints. Tocontinue VI execution, click on the Pause/Continue button. To clear breakpoints, clickon the set breakpoints with the Breakpoint tool.16. Turn off execution highlighting by clicking on it.17. Close the VI and all open windows by selecting Close from the File menu.Creating an Icon and Connector VIObjective: To learn to create your own VI icons. These icons are essentially sub-VI‘s(subroutines) that can be used within other VI‘s. In order to be used, icons must have terminalsfor wiring them into a VI. In this lesson, you will create an icon for the Convert C to F VI andassign the terminals of the icon to the digital control and indicator. You will use this VI againlater.Creating an Icon and Connector - Front Panel1. Open the Convert C to F VI.2. Open the Icon Editor by popping up in the Icon Pane (upper right corner) and choosingEdit Icon from the pop-up menu.3. Erase the default icon by double-clicking on the Select tool (broken rectangle) andpressing delete . Redraw the border by double-clicking on the Rectangle tool(unbroken rectangle).4. Create the icon shown on the top of the next page. Create the text with the Text tool (A).Double-click on the Text tool to change the font. Create the arrow using the Pencil tool.Shift-dragging (holding down shift while dragging the mouse) with the Pencil tooldraws horizontal or vertical straight lines.

5. Close the Icon Editor by clicking on OK when your icon is complete. The icon appears inthe Icon Pane in the upper-right corner of the Panel or Diagram window. The iconrepresents the VI in the block diagram of other VIs. An icon can be a pictorialrepresentation of the VI‘s purpose, or it can be a textual description of the VI or itsterminals.6. In the Front Panel window (note: this will not work in the Diagram window), define theconnector terminal pattern by popping up in the Icon pane and choosing ShowConnector from the pop-up menu .7. LabVIEW will select a terminal pattern based on the number of controls and indicatorson the front panel. In this example, there are two terminals—the deg C digital control andthe deg F digital indicator.8. Assign the terminals to the digital control and digital indicator using the Wiring tool. Clickon the left terminal in the connector and then on the deg C control. The left terminalshould turn a dark orange color. Now click on the right terminal in the connector andthen on the deg F indicator. Now the right terminal will turn dark orange.9. When you click in an open area of the panel, both terminals on the connector should beorange. This shows that both terminals are connected to floating-point values.10. A common LabVIEW convention is that the terminals connected to front panel controlsare located at the left side of the connector pane, while the terminals connected to frontpanel indicators are located at the right side of the connector pane. In other words, yourinput terminals are at the left on the connector pane, and your output terminals are at theright on the connector pane.11. Save the VI under the same name.12. Close the VI.

Thermometer VIObjective: You will build a VI that measures temperature using the temperature sensor on theDAQ Signal Accessory. The sensor outputs a voltage proportional to temperature. For example,if the temperature is 23 C, the sensor output voltage is 0.23 V. The VI also will have the optionto display the temperature in degrees Fahrenheit rather than degrees Celsius.NOTE: Use the (Demo) Read Voltage VI instead of Read Voltage VI. This VI simulates atemperature sensor.A. Begin by building this front panel (instructions follow).1. Open a new panel by selecting New from the File menu.2. Place the thermometer indicator in the Panel window.a. Pop-up in an open area of the Panel window and choose Thermometer from the popup Numeric subpalette.b. Type Temperature inside the highlighted text box and click the mouse button or theEnter button on the toolbar.c. Pop-up on the Thermometer and select Visible Items Digital Display.3. Rescale the thermometer control to display the temperature between 0 and 125. Usingthe Labeling tool, double-click on 100 in thermometer scale, type 125, and click the enterbutton on the toolbar. Change the precision of the displayed temperatures by poppingup on one of the numbers and selecting Format & Precision from the dropdown menu.Choose Automatic formatting and change 6 and Significant figures to 2 and Digits ofprecision, respectively. The precision of the Digital Display can also be changed fromthis dialog box by selecting Digital Display 0 instead of Scale in the dropdown menu inthe upper left corner.4. Place the vertical slide switch in the Panel window.a. Pop-up in an open area of the Panel window and choose Vertical Slide Switch fromthe pop-up Boolean subpalette. Type Temp Scale inside the text box and click themouse button or the enter button on the toolbar.b. Using the Labeling tool, place a free label, deg C, next to the true condition of theswitch. Place a free label, deg F, next to the false condition of the switch.

B. Create on-line documentation for all front panel objects and for the on-line help.1. Document the VI by choosing VI Properties from the File menu. SelectDocumentation from Category menu. Type the description of the VI in the dialog box:―This VI measures temperature using the temperature sensor simulator.‖Click on OK. You can recall the description by again choosing VI Properties from theFile menu.2. You can also document the objects on the front panel (or their respective terminals onthe block diagram) by popping up on the object and choosing Description and Tip fromthe object pop-up menu. Document the thermometer indicator and switch control.a. Pop-up on the thermometer indicator and choose Description and Tip from the popup menu.b. Type the description: ―Displays the temperature measurement.‖ and click OK.c. Pop up on the vertical switch control and choose Description and Tip from the popup menu.d. Type the description: ―Determines the scale (Fahrenheit or Celsius) to use for thetemperature measurement.‖ and click OK.3. Show the descriptions you created by again selecting Description and Tip from theindicator and control pop-up menu.C. Now build this block diagram using the instructions that follow.1. Select the block diagram objects.(Demo) Read Voltage VI (Functions Palette » User Libraries » BasicsCourse subpalette). This VI simulates the Read Voltage VI operation.Numeric Constant (Numeric subpalette). To insert a new value, doubleclick inside the numeric with the Labeling tool and type the new value.

Multiply function (Numeric subpalette). In this exercise, this functionmultiplies the voltage that the Read Voltage VI returns by 100.0 to obtainthe Celsius temperature.Convert C to F VI (Select a VI subpalette). Open Yourname.llb andselect the VI you wrote: Convert C to F. The icon you created can thenbe placed in the diagram as a sub-routine.Select function (Comparison subpalette). Depending on the value of theTemp Scale switch, the function outputs either the Fahrenheit (False) orCelsius (True) temperature value.2. Using the Positioning tool, place the icons as illustrated on the diagram and wire themtogether with the Wiring tool.Remember, if you need to see icon terminals, pop up on the icon and choose VisibleItems Terminals from the pop-up menu. You also can show the Help window bychoosing Show Context Help from the Help menu.3. Run the VI several times. Place the VI in the free-run mode by clicking on theContinuous Run button.4. Turn off the continuous-run mode by clicking on the Continuous Run button.5. Create the icon as in the previous lesson.a. Invoke the Icon Editor and erase the default icon.b. Draw an icon that represents the thermometer.6. Create the Connector as in the previous lesson.a. Pop-up on the icon pane in the control panel andchoose Show Connector.b. Assign the terminals to the switch and thethermometer using the wiring tool.D. Save the VI in your library and name it: Thermometer.vi.E. This VI is now complete and ready for use as a subVI in other VIs. The icon represents theVI in the block diagram of the calling VI. The connector (with two terminals) outputs thetemperature. Close the VI by choosing Close from the File menu.

Temperature Monitor VIObjective: To build a VI to measure temperature and display it on the waveform chart. This VIwill measure the temperature using the Thermometer VI you built in the previous lesson as asubVI.You will use this VI later, so be sure to save it as the instructions describe.A. Build the front panel below using the instructions that follow.1. Open a new panel and place a vertical slide switch (Boolean subpalette) in the Panelwindow. Label the switch Enable. You will use the switch to stop the acquisition. Popupon the switch and choose Boolean Text from the Visible Items. Use the Positioning toolto move the text to the right of the switch.2. Place a Waveform Chart* (Graph subpalette) in the Panel window. Label the waveformchart Temperature History. The waveform chart will display the temperature in real time.*NOTE: A Waveform Chart is different from a Waveform Graph – make sure that youselect the correct one. A chart displays data in real time as it is collected, like a chartrecorder. A graph displays the results only after the data collection is complete.3. Because the waveform chart legend labels the plot Plot 0 by default, relabel the legendappropriately. Using the Labeling tool, double-click on Plot 0 in the chart legend, typeTemp, and click outside the text area. The click enters the change. You also can selectthe Enter button in the toolbar to input the change.4. Because the temperature sensor measures room temperature, rescale the waveformchart to display the temperature. Using the Labeling tool, double-click on 10 in thewaveform chart scale, type 90, and either click outside the text area or press enter .Change -10 to 70 in the same way.

5. To change the precision of the numbers on the y-axis, pop-up on one of the numbersand select Formatting Change the formatting from 6 Significant digits to 1 Digits ofprecision.6. Change the y-axis label by clicking on it with the Labeling Tool and typing deg F.B. Create the block diagram using the instructions that follow.1. Select a While Loop from the Structures subpalette; then click in the diagram and dragthe loop around the enable switch and waveform chart icons. The loop can be enlargedby dragging a corner with the Positioning tool.2. Wire the ―Enable‖ switch to the Stop icon in the corner of the loop. Popup on the Stopicon and select Continue if True. The icon will now appear as it does in the diagramabove.3. Place your Thermometer VI (Select a VI. subpalette) inside the loop and wire it to thetemperature monitor.C. Save the VI in your library. Name it: Temperature Monitor.vi.D. Modification of the graph format.1. Return to the front panel and turn on the vertical switch by clicking on it with theOperating tool. Run the VI.The While Loop is an indefinite looping structure. The diagram within its border willexecute as long as the specified condition is true. In this example, as long as the switchis ON (TRUE), the Thermometer VI will take and return a new measurement and displayit on the waveform chart.2. Stop the acquisition by clicking on the vertical switch. This action causes the loopcondition to be FALSE (OFF) and the loop ends.3. You can format and customize the X and Y scales of the waveform chart to suit yourdisplay preferences and data. Pop up on the chart and select Y Scale » Formattingfrom the pop-up menu.Experiment with different X- and Y-axis grid options by clicking on the grid style selectorand choosing different styles for the axes from the sub-menu that appears. From thiswindow you also can experiment with scale styles, scaling factors, mapping mode, andthe format and precision of the axis displays. When you finish exploring these options,return the values to the ones shown above and click on OK or Cancel.

4. Clear the display buffer and reset the waveform chart by popping up on the waveformchart and choose Data Operations » Clear Chart from the pop-up menu. If the VI isrunning, select Clear Chart from the pop-up menu.5. Notice that each time you run the VI, you first must turn on the vertical switch and thenclick on the Run button.6. Modify the vertical switch so that you need not turn on the switch each time you run theVI.a. Stop the VI if it is running.b. Return the vertical switch to the ON position.c. Pop-up on the switch and choose Data Operations » Make Current Value Defaultfrom the pop-up menu. This will make the ON position the default value.d. Pop-up on the switch and choose Mechanical Action » Latch When Pressed fromthe pop-up menu.e. Run the VI. Click on the vertical switch to stop the acquisition. The switch will moveto the OFF position and return to the ON position after the While Loop conditionterminal reads the value.7. Now add timing to the loop so that it takes a data point every second. When you ran theVI, the While Loop executed as quickly as possible. However, you may want to takedata at certain intervals, such as once per second or once per minute.You can control loop timing using the Wait Until Next ms Multiple function (Time &Dialog subpalette). This function ensures that no iteration is shorter than the specifiednumber of milliseconds.8. Modify the VI as shown below, to take a temperature measurement once every second.9. The Numeric Constant wired to the Wait Until Next ms Multiple function specifies await of 1000 ms (one second). Thus, the loop executes once every second.10. Save the VI again under its current name.11. Run the VI. Try different values for the number of milliseconds.12. Close the VI.

Random Signal VIObjective: To implement timing of a data display by using a numeric control and waveformchart.Problem: Build a VI that generates random data and displays it on a waveform chart in scopeupdate mode. The VI should have a knob control on the front panel to adjust the While Looprate between 0 and 2 seconds. The panel also should have a switch to stop the VI. You shouldnot need to turn on the switch each time you run the VI. Build a front panel similar to the onebelow.Hints:Hide the waveform chart‘s legend using the Visible Items » Legend option.Use the Random Number (0-1) function (Numeric subpalette) to generate the data.Multiply the knob terminal by 1,000 to convert the seconds to milliseconds. Use this value as theinput to the Wait Until Next ms Multiple function (Time & Dialog subpalette).When you have completed the VI:1. Save the VI and name it Random Signal.vi.2. Run it.3. Close the VI.

Auto Match VIObjective: To pass data out of a While Loop through a tunnel.You will build a VI that generates random numbers until the number generated matches thespecified number. The loop count terminal keeps track of the number of iterations before amatch occurs.You will use this VI later, so be sure to save your work as Auto Match.vi.A. Build the Front Panel by creating one digital control and two digital indicators and labeling asshown below.1. Set the data range on the front panel controls.The Data Range option prevents you from setting a value that is not compatible with apreset range or increment. Your options are to ignore the error or coerce it to withinrange. A solid red border frames the control that is out of range. Set the range between0 and 100 with an increment of 1 by popping-up on the digital control and choosing DataRange from the pop-up menu. Uncheck the Use Default Range box by clicking on it,and fill in the desired Minimum, Maximum, and Increment values.2. Set the precision of the control and indicators on the panel.You can use the Format & Precision option to change the precision or to display thenumeric controls and indicators in scientific, engineering, or hour/minute/secondnotation. To change the precision to zero:a. Pop up on each control and digital indicator and choose Format & Precision fromthe pop-up menu.b. Select Floating Point, enter a 0 for Digits of Precision, and click on OK.

B. Create the block diagram to make this VI run.Some new functions:Round To Nearest function (Numeric subpalette). In this exercise, this functionrounds the random number between 0 and 100 to the nearest whole number.Not Equal? function (Comparison subpalette). In this exercise, this functioncompares the random number with the number specified in the front panel andreturns a TRUE if the numbers are not equal; otherwise, it returns a FALSE.Increment function (Numeric subpalette). In this exercise, this functionincrements the While Loop count by one.TunnelsThe black square that appears on the While Loop border is called a tunnel. Throughtunnels, data flows into or out of a looping structure. Data passes out of a loop after the loopterminates. When a tunnel passes data into a loop, the loop executes only after data arrivesat the tunnel.While Loop OperationThe loop in this exercise will execute as long as no match exists. That is, the Not Equal?function will return a TRUE as long as the two numbers do not match. Each time the loopexecutes, the iteration terminal automatically increments by one. The iteration count passesout of the loop upon completion. This value increments by one outside the loop because thecount starts at 0.C. Save the VI. Name it Auto Match.vi.D. Enter a number in the

Labview Exercises for Labview 7.0 Installation of Labview: 1. Install the Labview 7.0 software and drivers onto your computer. These files can be found by mapping a network drive to \\poohbah\labview, and by running the ‗autorun‘ file in the ‗Labview 7‘ folder. The serial num