How do I make a boolean indicator show 3 states instead of 2

[EngrStudent]

Boolean is 2-state.  I just wish I could make it like a stop-light.

Green is "go", yellow is "danger" and red is "stop".

Any suggestions how to do this?

[DuncanW. · Accepted solution]

Hi EngrStudent,

Unfortunately, LabVIEW does not currently offer support for strict Boolean controls with 3-state capability. However, there are numerous workarounds of varying complexity that will allow you to implement functionality similar to a stop-light.

This thread might be a good place to start:

3-State Control w/ Colors

This problem is also documented in a number of other threads on the forums already. I would recommend a quick Google search if the above thread is unable to help you.

Duncan W.

[aputman · Accepted solution]

There is an XControl here that is like a tristate boolean (if there is such a thing).  Haven't downloaded it to try it out but it looks nice.

[altenbach · Accepted solution]

By definition, a boolean only has two states, so it cannot be a boolean datatype.

LabVIEW has the mixed checkbox that I use occasionally.

in the more general case I would use a colorbox (that can e.g. be made to look like an LED).

... hmmm, I see that the above link already points to my similar response from 9 years ago. Nothing has changed! 😄

But there is also this idea that is worth voting for. 🙂

[Bob_Schor]

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@altenbach wrote:

But there is also this idea that is worth voting for. 🙂

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Yes, indeed!  Another vote added ...

Bob Schor

[altenbach]

Another option would be a picture ring.

[EngrStudent]

@altenbach,

I didn't like it being a boolean with 3 states.  To be a boolean it could have any number.  A binomial is intrinsically 2-state, but boolean techniques work with multinomials.  I think a trinary indicator is more technically correct, but I couldn't be sure folks would know what I meant.

I was hoping for a built in. 

[alexderjuengere]

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EngrStudent wrote:

I was hoping for a built in. 

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well, there exists a "3-Zustands Feld" or "Mixed Checkbox" under

Frontpanel>Elements>System>Mixed Checkbox

http://zone.ni.com/reference/de-XX/help/371361N-0113/lvhowto/configure_mixed_checkbox

[altenbach]

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@EngrStudent wrote:

To be a boolean it could have any number.

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According to Wikipedia, " the Boolean data type is a data type, having two values (usually denoted true and false),"

So, yes, any set with two possible values can be represented by a boolean (exactly one bit!), e.g. (500, -3), (Red, green), (light, dark).

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@EngrStudent wrote:

A binomial is intrinsically 2-state, but boolean techniques work with multinomials.  I think a trinary indicator is more technically correct, but I couldn't be sure folks would know what I meant.

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Why are you mentioning binominals?

Ternary logic is well defined, but these are not booleans and need more than one bit to represent the value. The mixed checkbox I mentioned earlier is more of a cosmetic thing, because you cannot do ternary logic with its value directly. I typically use it to represent (All, some, none) when selecting other items.
 

From reading your question, you simply want an indicator with a limited set of values. LabVIEW has plenty of those. Look at rings and enums. In particular you can use a picture ring indicator with three colored images (as I suggested already)  and you are already there. You can even give each state a name (e.g. red|green|Yellow). So yes, there are "built-ins" 😄

The color LED is useful for fancier UIs, e.g. when you want the color to change gradually between states.

[EngrStudent]

I was thinking of boolean in the sense of binary adder from boolean algebra, from my digital logic class. (link)

I'm sorry for any confusion.