Measure HIGH frequency with counter

I want to measure 1 Mhz range freq with lab PC 1200 board

Hello;
The maximum frequency that the source input of the counter can have a signal hooked up to is 8 MHz.
To measure a 1MHz signal, just connect that signal to the source pin of the counter, and use one of the examples that both NI-DAQ and Labview have to start your application.
Hope this helps.
Filipe A.
Applications Engineer
Naional Instruments

Similar Messages

Measuring high frequency with NI 9411

Hello,
I would like to measure the frequency of a TTL signal with the NI 9411 in a cDAQ NI-9178 chassis. The frequency ranges from 1.6-48kHz.
With the digital frequency counter examples in Labview, it's not picking up on the signal. Any advice?
Anna
Solved!
Go to Solution.

Hi Anna,
Could you tell me the name of the example VI that you are using? Also, you say that it is not picking up on the signal. Are you getting no data from the device at all? If this is the case, have you tested the device in MAX to make sure that this is not a hardware issue?
Thank you,
Eden S
Applications Engineer
National Instruments UK & Ireland

Measuring frequency with counter or analog input?

I have some frequencies which I need to measure. Some signals are digital and some are analog.
I have a PXI-6040E DAQ which has both counters and analog inputs.
I heard that you can measure higher frequencies with the counters than with analog inputs.
What is the range of frequencies an analog input can determine versus a digital counter?
Where is the cutoff that you must absolutely use a digital counter to determine the frequency?
Is the cutoff different for different DAQ cards? Or is generally the same.

Have you looked at the specs for the device? The max sample rate and the max counter input will be listed there. The max frequency for an analog input is based on nyquist sampling theory. Are you at all familiar with? It states your sampling frequency has to be at least twice the frequency you are measuring.
Since each device might have a different max sample rate, your last question is answered.

Measure pulse frequency with 4.7 volt peak amplitude

used two shipped Measurment Studio Vb.Net 2005 Examples:
1-Example 1 : CountDigEvents "MEASURES PULSE COUNTS" and Example 2: MeasDigFrequency_LowFreq1Ctr "MEASURES PULSE FREQUENCY"
2-Example 1 works fine measuring pulse counts , however Example 2 did not recognize pulse frequency , the pulse amplitude voltage is 4.7 volt peak
3-during testing used counter ch0 channle by connecting Sorce0 and Dgnd pins to signal source.
4-using Nidaqmx 9 and MIO-16xe-10 daq
5-pulse frequency around 10 khz
QUESTION:
-please advice what to do to make frequency measures ?
Thanks

Hi MyKat,
Note that the connections are different for edge counting and low frequency frequency measurements with one counter. For the latter, you'll need to connect the signal to PFI 9 rather than PFI8 as you did for edge counting.
http://zone.ni.com/reference/en-XX/help/370466W-01/mxdevconsid/eseriessigcounters/
Regards,
-Jim B
Applications Engineer, National Instruments
CLD, CTD

Measuring varying frequency with 9401

I need to measure a varying frequency with a 9401 in 9178 chassis. I am using an Express VI. I have the input connected to the 9401 terminal and can read counts just fine expect that the counts per second vary. I compared this to a scope and see that the pulse width varies and thus my frequency varies. When I attempt to measure frequency, I get errors that no data was measured. I also see the note in the Express VI to connect the input to PFI0. This I do not understand. Can someone help me?

I am using the DAQ Assist Exp VI. For grins, and to learn, I connected my signal wires to the PFI0 BNC and got an RPM signal. This answered my question if I really need to do this but it does not answer my question of why? At this point that does not matter because ultimately I am not after RPM or frequency. I am really after a steady pulse rate which I also learned is not possible. The system I am using has an inherent varying flow rate which results in a varying pulse rate.
So here is where I am at. I have two of my flow measurement systems in line measuring the same flow. They are indicating about 0.3% differece after accounting for thermal expansion of the fluid. The flow rate is on the order of 0.42 mL. I am then converting this to gallons for the user to better understand but that makes the number really small. I am suspecting that, because the flow rate is so small and because I am adding each second of mL flow, I am gettng an accumilation error with such small numbers even though I am using double-precision. My next attempt is to not convert to gallons until all the calculations are complete. This will allow larger values in the interium calculations.
Your thoughts?

Measuring Low Frequencies with LabVIEW and FieldPoint Using [c]FP-CTR-500/502

I am trying to use this example in a LabView 8.0 and a Field Point FP-CTR-502 module but without any sensor I get frequency and period values.
Is that possible to use this example with LabView 8.0 or not?
I am trying to use an anemometer Campbel Scientific A100R.
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3ED7556A4E034080020E74861&p_node=174404&p_source=External
Attachments:
Low_Frequency_Measurement_CTR_LV71.vi ‏193 KB

You can launch MAX from start\programs\National Instruments\Measurement & automation.
Concerning source signal wiring, you can have a look to the following link : http://zone.ni.com/devzone/conceptd.nsf/webmain/01F147E156A1BE15862568650057DF15?opendocument
Hope this helps,
Manuel R
AE dans une autre vie

DAQmx Error 89137 When trying to make a high frequency measurement.

I am using a PCI-6602 Timer/Counter for multiple measurements on a serial interface...
I have the clock line connected to Gate0, the enable line to Aux0 because I need to make a two-Edge seperation measurement between the two later...
But I also want to make a "Period/Frequency Measurement (High Frequency with Two Counters)" measurement...
This requires that the signal to be measured is on Source0...
I implimented the following Code:
void meas_FP_Freq(float64 *Freq0, float64 *Freq1)
TaskHandle CLK0_Freq, CLK1_Freq;
DAQmxCreateTask ("FP_CLK0_Freq", &CLK0_Freq);
DAQmxCreateTask ("FP_CLK1_Freq", &CLK1_Freq);
DAQmxConnectTerms ("/Dev3/PFI38", "/Dev3/Ctr0Source", DAQmx_Val_DoNotInvertPolarity); // Gate0 to Source0, No Error....
DAQmxConnectTerms ("/Dev3/80MHzTimebase", "/Dev3/Ctr1Source", DAQmx_Val_DoNotInvertPolarity);
DAQmxCreateCIFreqChan (CLK0_Freq, "Dev3/ctr0", "", 6000000, 6500000, DAQmx_Val_Hz, DAQmx_Val_Rising, DAQmx_Val_HighFreq2Ctr, 0.001, 4, ""); // High freq measurement
DAQmxCreateCIFreqChan (CLK1_Freq, "Dev3/ctr1", "", 6000000, 6500000, DAQmx_Val_Hz, DAQmx_Val_Rising, DAQmx_Val_LowFreq1Ctr, 0.001, 4, "");
DAQmxReadCounterScalarF64 (CLK0_Freq, 3.0, Freq0, 0); // Run-Time Error -89137 Specified Route cannot be satisfied..etc
DAQmxReadCounterScalarF64 (CLK1_Freq, 3.0, Freq1, 0);
DAQmxDisconnectTerms ("/Dev3/80MHzTimebase", "/Dev3/Ctr0Source");
DAQmxDisconnectTerms ("/Dev3/80MHzTimebase", "/Dev3/Ctr1Source");
DAQmxClearTask (CLK0_Freq);
DAQmxClearTask (CLK1_Freq);
The "Low Frequency" method works fine, but the resolution is too low...
Every help file I've read indicates I can use different PFI inputs for measurements... What am I missing?

Hi,
The reason that you are getting the error is the PFI lines are being reserved twice. You don't need the DAQmx Connect Terms functions in your code because the DAQmx driver does this for you automatically. If you still receive an error after doing this, try to changing the low frequency counter number. I hope this helps you with your application.
Regards,
Hal L.

High frequency measurement 2 counters range

Hello,
I know this info is somewhere but I can't find it.
When using a Counter/timer to measure frequency there are multiple methods.
i.e. Low Frequency with 1 counter and high frequency with 2 counters.
What is the definition of a "low frequency" and what is the definition of a "high frequency"? i.e. low frequency = frequencies below 100 Hz
Also what is the definition of a "large range"?
Thanks
Dan

Hi Dan
There isn't a specific bandwidth that is defined for use with either the one-counter or two-counter method. However, located in the NI-DAQmx help file there is a section detailing the quantization errors that arise when using either method with a variety of input frequencies. By referring to this information you should be able to determine which method will produce the smallest error in your application and hence which method will be preferable. This help file also explains the errors associated with the large-range two-counter method.
To locate the help file, you should select Start»All Programs»National Instruments»NI-DAQ»NI-DAQmx Help, and search for 'quantization error'.
I hope this helps, just let me know if you'd like anything clarified or if you have any other questions on the matter.
Regards
Jeremy T
Technical Marketing Engineer
National Instruments UK & Ireland

Measure frequency with 2 counters

Hello,
I'm measuring a digital frequency signal using a PXI-6602 module using the 'high frequency with 2 counters' method. From the examples I have found, it seems that you specify only the counter which is doing the measuring and the measurement time. How does LabVIEW know which counter is used to generate the HF pulse reference train, for example:
ctr 0 - measuring 200kHz signal
ctr 1 - generating 50kHz signal
Do I independently set up and start the ctr1 generation, and as log as it starts before the measurement commences, does LV then sort it all out without any other input?
Thanks
Dave

You should connect the signal (whose frequency needs to be measured) to Ctr-1, and there gonna be an internal connection between the output of the first counter and the gate of the second counter (as described here).
You may want to check this link as well.
I am not allergic to Kudos, in fact I love Kudos.
Make your LabVIEW experience more CONVENIENT.

Trying to measure frequency with the cFP-CTR-502. Can't get tutorial to work!

Hello,
I am trying to measure the frequency of a
signal that I'm counting using the cFP-CTR-502. I can successfully
count pulses but I what I really need to know is the RATE of counts
(counts/s or the frequency). I have found some Labview programs that
supposedly do this that I've downloaded from ni.com (link below). The
concept makes sense of using a gate and output but the programming is
crazy - at least the program in the link below is.
1. Is there an easier way to measure the frequency of counts?
2. Why will the program from the link below ( frequency_measurement__ctr_.vi
) not work on my system? I get an error everytime I run it. Could I be
missing some VI's necessary for it to run? Or is it from another
LabView version that is not compatible?
The
entire error is: -32810 occured at FieldPoint initialization failed.
Possible causes, 1. Missing or corrupt configuration file; 2. Failed to
create call backs. : FP Open.vi
Link for program: http://sine.ni.com/devzone/cda/epd/p/id/4682
Thanks in advance for all your help and time!
Sam T

Sam,
Have you tried the example titled Frequency Measurement.vi that ships with LV?

Measure current frequency

hi, can someone help me... i am doing aproject to count a current pulse and the data can be manipulate to get the pulse frequency..the sensor i use is tetronix A622 current probe(http://www2.tek.com/cmsreplive/psrep/13510/60W_15081_0c_2009.05.15.11.07.56_13510_EN.pdf) and i have a daq 6024 and daq 6008 series..can someone please give me an idea how can i done this...i had try with counter vi but it seems the vi only can coun squre wave and can't count current pulse wave
Attachments:
pulse count.vi ‏84 KB

Use DAQ Assistant to acquire signal from Analog Input, and use Tone Measurement VI to measure its fundamental frequency, but be reminded that highest measurable frequency is analog input sampling rate/2.
If you wish to measure higher frequency, you must build a pulse shaping circuit and input pulse to counter for frequency measurement.

How to measure and log frequency with fieldpoint CTR

Hi,
I am developing a data acquistion and control system for an engine dynamometer using the fieldpoint modules and Labview. One of the most important signals is the engine speed, measured in RPM. The RPM signal is a 0-12V pulse where one pulse equals one revolution of the engine. As well as being an important piece of data for later analysis, engine RPM will also be in the input into a PID controller, so the signal must be both accurate and have a high measurement frequency.
Currently I am using the FP-CTR500 modules to measure the frequency of the signal. I am already aware of the included frequency measurement VI example, as well as the one posted before for low frequency measurements, and I have gotten both to work with my setup. I would be using the low frequency VI becuase the max frequency measurement would be in the 200Hz range.
The first problem I am having is with the structure of the VI and how the data is output. The case structure in the VI activates when the counter is read and resets the counter, then switches to the next case. I would like the RPM number to output out of the case structure into a write_to_file VI and PID controller input. The problem is that when the case switches, the counter is reset to 0, which will be recorded in the written file.
This is some example output data (RPM):
1232
0
2321
0
2400
0
2521
0
The data is being written correctly, but of course I can't have 0 readings when the case structure changes. This would be especially problematic when input into a controller VI.
The next problem I am having is with sampling rate. If I were to use the low frequency measurement VI, the sampling rate of RPM would be variable based upon the the speed of the signal. Or, the original frequency measurement VI has an adjustable sampling rate. Of course, in my system there are a number of other signals that need to be recorded at the same time. I have found that as I am collecting data, the "write to file frequency" is entirely dependent on the read frequency of the frequency measurement. Therefore, if I had set the read frequency VI to read at 1 Hz, data will be recorded only every 2Hz. Ideally I would like an overall measurement frequency of all channels (mix of analog and digital) to read between 20-50Hz, but if I am limited by the frequency measurement.
Any ideas on how to solve this problem, either through Fieldpoint or Labview?
I can post my VI if this help.
Thanks,
Huang

Thanks for your reply.
I should probably describe my current setup before I go into anymore details with the problem. As for my specific setup, I am using an FP-1000 connected with an AIO600, AI110, CTR500, and TC120 all running through the RS232 line to a desktop running labview 8. The actual counter module is reading a tachometer signal output from a separate engine controller. THe output is a 0-12V ON 50% duty cycle signal. As for data logging, i am simply using a "write to measurement file" Express VI. I have a while structure which holds all of the express VIs which access the fieldpoint IO, and these are all routed to the "write to" VI.
As for the specifics of the data logging problem, as I said, when I set the count frequency of the "Fieldpoint Frequency Measurement" VI to 1Hz, (which means the VI calls the case structure at 2Hz), the "write to measurment file" VI is called at the same rate (2Hz). Which means that the overall logging rate of the VI is only 2Hz. Is there someway to decouple this?
I was able to solve the problem of calling the frequency variable from the case structure by using a local variable which is called outside the case structure.
And now I have been having a lot of problems with reading the actual frequency from my engine controller. THe actual signal will only range from 0 to around 200Hz. I noticed, by comparing the actual signal to what was being read in my labview program, that after around 80Hz the signal increases by around 1.5times more than the actual signal. ie. Actual signal = 100hz, Read Signal = 150Hz. After trying to figure out what was the problem, I decided to change the Noise Filter settings to 200Hz. It actually worked for all the frequency ranges up to around 150Hz but after that the filter attenuates the signal to the point where the actual signal is 160Hz, but is being read at 100Hz. My question is if there is a way to change the actual filter setting outside of the 2 given setpoints (200hz and 40khz) or if you have any other suggestions on how to fix this problem? I was thinking of creating a noise filter input in MAX so that i could play with the values in Labview, but am i only limited to those two filters?
Thanks again for your help,
Huang

High frequency measurement

I need to measure a frequency around 3 Mhz the signal is in bursts.
I have the example 2 counter.vi working with a siggen with a continuous output but can't get a reading on the burst.
Below is the vi and scope shots of the signal I need to measure.
Attachments:
DAQ Counter.png ‏41 KB
freq1.png ‏46 KB
freq2.png ‏44 KB

johnsold wrote:
I suspect that the best way for you to measure the freqeucny of the bursts is to use an analog acquisition with a sampling rate of at least 10 MHz (higher is probably better). Then do an FFT on each burst. The images you posted earlier show about 30 cycles in a burst. That is enough to get a reasonable response from an FFT. You could also detect zero crossings and calculate the frequency from that. FFT may be easier.
Does the frequency vary within a burst? Does it vary from one burst to the next? What is the range of frequencies in the bursts? What frequency resolution do you need? How fast do you need to analyze the data? Between bursts or seconds later?
Lynn
The frequency is constant in each burst and is the the same from one burst to the next.
Resolution does does not need to be real acurate .5 mhz would work, but the more acurate the better..
I have lots of time to analyze the data at least 30 seconds to capture and analyze.

How to use counter to test High frequency ?Any tutorial ? Thanks!

thanks

Hello Shenzhengpib,
There is an example program that comes with LabVIEW called Meas Dig Frequency-Buffered-Cont-High Freq 2 Ctr.vi. This can be found in the Example Finder (Help Menu>>Find Examples) under Browse Hardware Input and Output>>DAQmx>>Counter Measurements>>Digital Frequency. Please let me know if you have any questions. Have a great day!
Sincerely,
Marni S.

Can I measure frequency with a SCXI-1120 module and SCXI-1320 terminal block?

I am attempting to measure a square wave from a directional encoder to display RPM of a dynamometer. The waveform will have a frequency of 0-4KHz, with 3.6KHz being nominal, at about 5volts RMS. How can I measure the frequency of this waveform with the hardware I am currently using? In addition to what is listed above, I am using a PCI6034E GPIB card and LabView software.

In order to measure frequency, I would not recommend to use the SCXI-1120, but the SCXI 1126, which is a programmable isolated F-to-V module.
If by any reason you do not want to use SCXI-1126, then I would suggest to use the counter/timers of your board. The counter/timers are TTL compatible, and are the devices that we mostly recommend for doing precise frequency measurements.
In order to have access to the counter/timers of your board through your SCXI chassis, you will need SCXI-1180, which is basically a feedtrhough panel for your DAQ board.
Once we have access to the counter/timers through the SCXI chassis, we can proceed with the coding.
I found a pretty good webpage that clearly explains how to perform frequency measurement with the DAQ-S
TC counter/timers (DAQ-STC is the type of counter/timer chip that you DAQ device has). Here is the link to it:
Pulse Width & Frequency Measurements
As you will see, this link contains tutorials, application notes and example programs. I would recommend to pay special attention to the example program called: DAQ-STC: Measuring frequency.
Good luck with your application!

Measure HIGH frequency with counter

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