When using the default LED indicator in LabVIEW in my test projects, I found that the two statuses of it is not enough. For example, we can use a LED with red False status to indicate test failed and green True to indicate test passed, then what we can do with the LED before the test finish? The test result is still unknown, red and green are not proper. In this situation, we need a yellow Unknown status with the LED indicator.

The following is how I build a tri-state LED indicator:

First create a new VI, place a enum control and a LED indicator on the front panel as below:

Then edit the enum’s properties as bellow:

And here is the diagram of this VI:

This VI can be called by other VIs. We can use it to make LED indicator to display three colors for three different states.

This VI can be downloaded here: Tri-State LED Indicator.