You are here

Home » Introduction to G Programming » Introduction to G Programming

While Loop

26 July, 2019 - 09:47
Available under Creative Commons-ShareAlike 4.0 International License. Download for free at http://cnx.org/contents/5b6e61df-b830-48cb-9764-94696cb47c80@1.3

The next program will generate Fahrenheit values and convert them to Celsius until a condition is met to stop the iterations in a While Loop. In the Block Diagram window, select the While Loop structure by clicking on it from the Functions » Programming » Structures menu.

Click and drag to create the While Loop structure.

media/image57.png
Figure 1.56 While Loop Structure 
media/image58.png
Figure 1.57 Creating a While Loop 
media/image59.png
Figure 1.58 While Loop 

In the Front Panel window, create two numeric output arrays. Label them Fahrenheit and Celsius.

media/image60.png
Figure 1.59 Numeric Output Arrays 

Re-arrange the diagram as in While Loop Diagram .

media/image61.png
Figure 1.60 While Loop Diagram 

From the Functions menu, select Multiply function and a couple of numeric constants. Type in 20.0 and 300.0 for the numeric constants. Select the Fahrenheit to Celsius.vi and drop it inside the While Loop. Re-arrange the diagram to look like Generating Fahrenheit Values

media/image62.png
Figure 1.61 Generating Fahrenheit Values  

From the Functions » Programming » Comparison menu select the Greater or Equal operator.

media/image63.png
Figure 1.62 Greater or Equal Function
Description

Wire the While Loop components as shown in Generating Fahrenheit Values & Stop Condition.

media/image64.png
Figure 1.63 Generating Fahrenheit Values & Stop Condition  

Wire the output of the Multiply operation to theFahrenheit and the output of the Fahrenheit to Celsius function to the Celsius numeric output arrays. The connections between the While Loop and the Fahrenheit andCelsius arrays are broken (see Broken Wires).

media/image65.png
Figure 1.64 Broken Wires 

To repair the broken connections, roll over the mouse pointer to the Loop Tunnel.

media/image66.png
Figure 1.65 Loop Tunnel  

Right click on the Loop Tunnel and select Enable Indexing from the pop-up menu.

Figure 1.66 [/topic/body/fig/title/title {"- topic/title "}) Enable Loop Indexing (title] 

This enables values to accumulate and store the results into an array. Repeat for the Celsius array.

media/image68.png
Figure 1.67 Broken Wire Repaired  

Each iteration of the While Loop in this program generates an i ×20 Fahrenheit value and converts it to Celsius. The While Loop stops iterating when the generated Fahrenheit value is greater than or equal to 300. The resulting arrays are stored in the Fahrenheit and Celsius numeric output arrays.

Save the program as Fahrenheit to Celsius While Loop.vi and run it. The program generates the following results:

media/image69.png
Figure 1.68 Fahrenheit to Celsius While Loop 

Fahrenheit {0, 20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 240, 260, 280, 300}

Celsius {-17.7778, -6.6667, 4.44444, 15.5556, 26.6667, 37.7778, 48.8889, 60, 71.1111, 82.2222, 93.3333, 104.444, 115.556, 126.667, 137.778, 148.889}

media/image70.png
Figure 1.69 Fahrenheit and Celsius Arrays 
  • 1515 reads