Target reference marker in LV 8.6 - dial or slider

[tmunsell]

I posted this question in another forum, but I think it was the wrong area.

Basically, what I'm trying to do is to create a target marker on a slider bar indicator.

More details:

I am using a few slider bars and dial indicators to show turbine engine indications.  There are a few indicators that I would like to show a reference (target) mark where the engine is supposed to be running.  For instance, our maximum operating EPR (engine pressure ratio) is based on ambient air temperature.  I have created a csv file from the OEM performance charts (x=degF, y=EPR).  I'd like the indicators to use that data to show the target as a line or any other easily viewable marker for the engine operator to use as a "do not exceed" mark, while still using the fill option for actual engine EPR.

Is this possible in LV?  I can't seem to find anything like this on this site or Google.

Thanks in advance!

[Z'atari]

Hey Todd,

If you are trying to set a changing Max or Min allowable value for an input control, you can create a property node for those specific properties as shown in the picture. This way, instead of using a marker, the input value will be coerced if it exceeds your max values.

Hope this helps!

[tmunsell]

Thanks for the reply!  I'm not sure if that will work... unless I'm misunderstanding you.  I don't know much about property nodes.  I'm still fairly green when it comes to LV, and programming in general.  The data displayed needs to be accurate, and not coerced to another value.  I just need a simple marker that can be displayed on, or immediately above/below to the pressure slider.  Right now we have to manually reference the chart, which is old and hard to read for those of us with failing eyesight (haha), so it would be great if the computer can automatically display the target pressure right on the slider so we won't have to keep referencing the chart whenever the air temperature changes, which can happen several times during a test.

I'm really surprised that I can't find anything in LV that will allow this.  It would be a very useful feature, since most "running" machines have specific limits.  It would be an excellent visual reference.  Even very old aircraft gauges have "bugs" that you can set for target altitudes, speeds, etc.

I'll read up on property nodes and see if I can figure them out.  Thanks again

PS... I just noticed that you mentioned a "input control".  I'm only using a slider indicator with data from a sub-VI from our DAQ channel.  There is no control used for this reading.

11-12-2010 03:12 PM

Hey Todd,

If you are trying to set a changing Max or Min allowable value for an input control, you can create a property node for those specific properties as shown in the picture. This way, instead of using a marker, the input value will be coerced if it exceeds your max values.

[johnsold]

Todd,

You can add sliders or needles from the pop-up menu for the controls.  Will that do what you want?  I am not sure if there is any simple way to disable one while allowing the user to change the other, but you could use property nodes and the event structure to detect the changes and restore the original value.

Lynn

[tmunsell]

I've attached a screenshot of the front panel I'm working on.

I know how to display the target EPR in numerical format (in the red circle), but I'm trying to have it appear on the slider (like the green line) as well.  If this isn't possible, no biggie.  It would just make engine runs easier for the operator.

[tmunsell]

Hmmmm... now that's something to think about.  🙂  I'll see what I can come up with this weekend.  If I can have the "target" EPR show on a slider from right to left, and the live engine data from left to right, then it may work.

[RavensFan]

Try something like this.

[tmunsell]

Thanks for the sample, but could you save it for version 8.6 or earlier?  I can't open it.  Thanks again!

[Matt_W1]

here's Ravens Fan's idea, transparent control over indicator, with some event logic to color the zone, depending on whether you're in it.

[tmunsell]

Thanks!  I'll check it out this week.