Program a VI that takes a number from one Knob adjustable in the range 0 to 50, and it turns on an LED if the number is between 10 and 20.
Click on File>New VI. Click with the right mouse button inside Front Panel window to open the Controls popup and choose a Knob (that you can find, for example, following the path Express>Numeric Control). Do the same thing to put LED.
In Block Diagram window click with the right mouse button inside to open Functions popup and choose Less or Equal and Greater or Equal (that you can find, for example, following the path Express>Arithmetic & Comparison>Comparison).
Then choose two Numeric Constant (following the path Express>Arithmetic & Comparison>Numeric).
Connect everything as shown. Change the Knob range between 0 and 50 and write 10 and 20 in the two Numeric Constant.
You can download this VI for LabVIEW version 2010 and subsequent from here: 20150424_Knob_LED_and_comparisons_.vi