frequency measurement

[eesen]

Hello,

I have two DAQ card. PCI 6143 and PCI 6123. I get them to measure analog and digital signals. But now, ı need to measure some of the analog and digital signal's frequency. Frequencies of the signals are not high (Usually up to 110 hz) Can I (and how) make frequency measurement by using anolog input channels of PCI 6143 and PCI 6123. I need precious measurement but for now ı do not want to buy more hardware.

Best regards

[Erik_J]

Hey eesen,

If you would like to measure the frequency of a digital pulse train, you can use one or both of the counters on either your PCI 6143 or PCI 6123.

If you are using LabVIEW, an example can be found in Help » Find Exampels » Hardware Input and Output » DAQmx » Coutner Measurements » Digital Frequency » Meas Dig Frequency-Low Freq 1 Ctr.vi


You will need to use software to measure the frequency of an analog input.

If you are using LabVIEW, please see this KnowledgeBase (example included) on how to make an analog frequency measurement.

Regards,
Erik

[eesen]

Thanks for reply and sorry for late answer.

I have many signals which i should measure frequencies so i can't use counters. (Number of counter is not enough)

I try to use "tone measurement vi" and "Tone extraction vi" but they consume long time. I'm using Labview RT. In knowledgebases about LabVIEW Real Time programming  it is recommended that "Try not to use express vi"

"Tone measurement vi" and "Tone extraction vi are express vi's.

I need an alternative solution to measure frequency.

Message Edited by eesen on 03-29-2007 07:31 AM

[MickeyD]

Hi,

There are non express VIs that can perform the tone extraction measurments for you.  They are located under the Waveforms Pallette.  Go to Waveform>>Analog Waveform>> Waveform Measurements.  There will be Extract tone and Extract Multitone VIs.  You could also just search for the Extract Tone VI.  That should give you the functionality you need.  Let me know if you have any further questions about what VIs you should use. 

Have a great week,

Michael D
Applications Engineer
National Instruments

[eesen]

I tried vi that you said and they woks well

Thanx