LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

New LV2010 VI: High Resolution Relative Seconds

There is a new VI in LV2010 which returns a high-resolution tick count, however it is not on the palettes, and there appears to be no documentation for it.  It is called <vilib>:Utility/High Resolution Relative Seconds.vi

21179i8B1F40AA2731F4DF

This is present on Windows 32-bit (at least).

Message 1 of 15
(12,317 Views)

Wow, that's a neat VI.  I didn't know about it either.  I checked its diagram...just a callback into an internal LabVIEW function...no cool hidden functions or anything...

0 Kudos
Message 2 of 15
(12,311 Views)

Interesting.. :).

 

(Of course we could have made our own, along the lines of this tool ;).)

0 Kudos
Message 3 of 15
(12,304 Views)

@Darren wrote:

Wow, that's a neat VI.  I didn't know about it either.  I checked its diagram...just a callback into an internal LabVIEW function...no cool hidden functions or anything...


My version of that vi is password protected. If it nothing fancy why password protect it?



Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)
Message 4 of 15
(12,258 Views)

It is also present in the Mac version.

 

Coq Rouge,

 I think one of the NI people said that VIs in vi.lib which are not on the palettes are subject to change and are not recommended for routine use.  These are often password protected, even though they do not contain any great secrets.

 

Lynn

0 Kudos
Message 5 of 15
(12,243 Views)

@johnsold wrote:

It is also present in the Mac version.

Coq Rouge,

 I think one of the NI people said that VIs in vi.lib which are not on the palettes are subject to change and are not recommended for routine use.  These are often password protected, even though they do not contain any great secrets.


That sound at least reasonable. By the way is this VI used in some example, or somewhere else? Just curious 😉 

 



Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)
0 Kudos
Message 6 of 15
(12,231 Views)

 


@Darren wrote:

Wow, that's a neat VI.  I didn't know about it either.  I checked its diagram...just a callback into an internal LabVIEW function...no cool hidden functions or anything...


I think we need a better explaination of what the VI output means.  

21263iFD1A9FE509AB6F9B

 

 

Playing around I created this snippet-  Interesting results? Especially the Total elapsed time / mean = 0.5


"Should be" isn't "Is" -Jay
0 Kudos
Message 7 of 15
(12,220 Views)

Jeff - not quite sure what you're doing here.  The loop is subtracting the current tick count from the previous difference -- so the first value in your array is negative near zero, and the rest are getting more and more negative.  The rest is pretty much meaningless - and if you show more digits on the division, you see it's almost 0.5 but not quite, and with a little thought, it will be obvious why that's the case.

 

The output of this function appears to be simply a high-res tick count (with a precision in the sub-microsecond range) that rolls over at some value - no idea what the "zero" is, but it seems arbitrary.  So using it will probably require a check of it being reset.  Perhaps someone with access to the block diagram can make a more definitive statement.

 

I don't think it's used in an example - I just noticed it in the directory.

Message 8 of 15
(12,179 Views)

DOH


"Should be" isn't "Is" -Jay
0 Kudos
Message 9 of 15
(12,131 Views)

Just wiring before coffee.  Not a good plan for me.

 

Fixing the code yields a open loop resolution of @1.2uSec with a Std dev variying with other processes being run.  Hmmm.  almost could use it to calculate the rest of the CPU load.....


"Should be" isn't "Is" -Jay
0 Kudos
Message 10 of 15
(12,121 Views)