LabVIEW

[James_R]

what is the difference between local variables and property nodes concerning best practices and performance  ??

Thanks

James

[Darren]

If possible, you always want to pass data to/from your front panel controls/indicators with wires.  If this won't suffice (parallel loops, e.g.), then you will want to use locals.  Try to avoid using the "Value" property unless you must write to your controls/indicators in a subVI.  The "Value" property is very slow compared to locals due to threading issues associated with property nodes.

Hope this helps,

-D

[altenbach]

Since you compare the two in one sentence, you must mean "Value property nodes".

As Darren said, property nodes are expensive. Check out my speed comparison VI in this old thread:

http://forums.ni.com/ni/board/message?board.id=170&message.id=153611#M153611

(Of course if you need to write to a signaling value property in order to fire an event, a local variable won't work. You need the property node.)

[Travis_M.]

Hello all,

To take it one step further, the speed hit comes from the fact that these items run in the UI thread along with all of your other user interface actions (speed), and copies are always made of the data (performance AND speed)!  Check out the "LabVIEW Performance and Memory Management" tutorial -- while a little old its concepts are still dead on and it does a great job of explaining the details of these issues.  If you need to pass data from/to parallel loops or sub-VIs consider putting the data in some sort of container (like a single element queue), and passing the container around.

Hope this adds just a little more insight!

Message Edited by Travis M. on 02-08-2006 02:21 PM

[Rajmohan]

Really good Thread thanks

[vinod00]

Hello travis could you please pour in some more information on Property node concept and whn can it be best used?? Thanks in advance.