Measuring Freq (ADC11)

[BentRods]

Hi All

In the attached  VI,

the Block Diagram is currently reading Voltage and working ok, but I would like to know how to measure frequency from the VI ? 

any suggestion or example's would be appreciated.

The ADC11 is attached to LPT1 thats able measure DC Volts, AC Volts, dB and Frequency.

btw I had previously contacted PICO for support.....  they could not help.

TIA

BentRods

[Robert M]

The VI's you posted are simple dll wrappers.  In order to measure frequency, you will need to know which function in the dll to call and what its parameters should be.  If PICO (I'm assuming they developed the dll?) can't help you, I'm not sure who will be able to.  You need the full dll documentation.

Good luck,

[Dennis_Knutson]

I had a look at the documentation for the device and as far as I can tell, the device is only a simple 11 channel A/D with 1 or 2 digital outputs. Frequency, db, etc. would have to be calculated unless you have some sort of converter attached to it.

[BentRods]

Thanks for the replies,

yes there is a converter attached to LPT1 , at the heart of it is a TLC2543 from TI.

the reply from Pico lack's detail, I had kinda felt that this was all done from within the software , there is a brochure thats gives details about calling the adc1132.dll file but no mention of Freq,  I will try to find out some more info. 

BentRods

[BentRods]

Thanks Robert

the only info I have on this is the attached pdf, I am trying to get more info from Pico about this they are usually helpful but anything to do with that VI is not very well supported, it sounds like the person(s) have moved on .

BentRods

[Robert M]

The pdf doesn't mention any functions that return frequency data.  I imagine the device only returns voltage information over time, allowing you to calculate frequencies post-acquisition.

[BentRods]

The reply from pico was.....

Snip>> "The ADC11 will not convert readings into frequency. This is performed by the software.
You may be able to do this with a Labview tool. " <<

I did ask for more details .... shall wait and see.

I can read a Voltage from the vi ok, i also tried  to measure a Sq wave signal that was  a 50% duty cycle on one of the channels but I didn't see any results in the graph of my vi, btw when I input a simulated signal into the "Tone" it's ok , should this be filtered first perhaps ?

Thanks

Bentrods

[Dennis_Knutson]

"yes there is a converter attached to LPT1 , at the heart of it is a TLC2543 from TI."

That is just the A/D for measuring a voltage. what I was asking was whether you had an external Frequency to Voltage converter hooked up someplace. How exactly are you trying to measure frequency? Are you just using the VI you posted? If so, that won't work unless you are calling it in a loop and building a waveform from repeated measurements. And even in that case, your frequency measurement is bound to be inaccurate becasue you are then depending on software timing for the acquisition. What do you mean by "input a simulated signal into the "Tone""? What "Tone" are you talking about? I think what you have to do is figure out a way to to get a block of data back as an array using the adc11_get_values function in the DLL. I believe this will use the internal clock of the device to acquire data. You will have to make you own functions that use the Call Library Function Node. For information on how to use this, Go to Help>Search the LabVIEW Bookshelf>Using External Code in LabVIEW. There are shipping C/C++ and Visual Basic examples that you may want to look at as they seem much more complete than the LabVIEW one.