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

Similar Messages

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.

New M Series DDK Example: High Frequency Measurement with 2 Counters

This example demonstrates how to configure two counters on an M Series device to measure a high digital frequency. One counter generates a continuous pulse train of a set frequency while the other counts the external signal using the pulse train to latch values. Data is transferred via DMA.
Use this example to add high digital frequency measurements or DMA data transfer for counter input to your driver.
Please let me know if you have questions or problems. Thanks :-)
Joe Friedchicken
NI VirtualBench Application Software
Get with your fellow hardware users :: [ NI's VirtualBench User Group ]
Get with your fellow OS users :: [ NI's Linux User Group ] [ NI's OS X User Group ]
Get with your fellow developers :: [ NI's DAQmx Base User Group ] [ NI's DDK User Group ]
Senior Software Engineer :: Multifunction Instruments Applications Group
Software Engineer :: Measurements RLP Group (until Mar 2014)
Applications Engineer :: High Speed Product Group (until Sep 2008)
Attachments:
gpctex5.cpp.gz ‏4 KB

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.

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.

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.

High frequency power measurements

Hey,
I'd like to know if there are developments in measuring electrical high frequency signals with labview without using an extern power analyser. At the moment i'm using a yokogawa power analyser but i'd like to know if it's possible to log HF signals without the help of a power analyser... Are there NI products on the market for this purpose?
Thx,
Andy

Hello,
In the case of frequencies up to 200 KHz, NI can provide several solutions using the 'standard' data-acquisition boards or digitizers (scopes), from a low to very high accuracy solutions.
A good solution can be one of the high speed M-series boards (PCI-625x). These boards have up to 32 multiplexed channels with a resolutions of 16-bit at a speed of 1 MS/s (500 KHz).
A better solution would be a S-series boards. These data-acquisition boards sample all input channels simultaneously. We have boards with 2, 4 and 8 channels and sample frequencies of 10 MS/s (up to 5 MHz if needed). S-series board are the boards with product numbers PCI-61xx.
The best solution is to use a digitizer (scope). Also here a lot of possibilities going from low to higher bandwidth and resolution.
The most flexible is the PXI-5922. A 24-bit digitizer if you sample @ maximum 500 KS/s. This board only exist in the PXI platform.
Then NI has 8-bit digitizers (normal resolution for scopes) from 15 till 125 MHz bandwidth. If you need a higher resolution they have solution up to 14-bit (very high for scopes) @ 100 MHz.
Please give your local NI Office a phone call.
They have technical engineers who can discuss your needs and provide you a solution.
Best regards,
Joeri
National Instruments
Applications Engineering
http://www.ni.com/ask
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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

6602: How to use 8 counters simultaneously in C++ using traditional Daq for frequency measurement

Hi Everybody;
I'm new to Ni-DAQ cards and working on NI PCI-6602 Card in Borland C++, I should use Traditional DAQ for my project. Now I want to use all the 8 counters simultaneously for frequency measurement.
1.Where should I connect my External signal, to source or gate, at present I have connected to source.
2. How to set parameters and start the counters simultaneously, what are the parameters to be set for frequency measurement.
3.How to start counting.(parameter settings)
4.Should I set any PFI Lines or by default are they set to counters.
status = GPCTR_Set_Application (1, gpctrNum, ND_SIMPLE_EVENT_CNT)
status = GPCTR_Change_Parameter (1, gpctrNum, paramID, paramValue)
iStatus = GPCTR_Watch(1, gpctrNum, ND_ARMED, entityValue);
status = GPCTR_Watch (deviceNumber, gpctrNum,ND_COUNT, entityValue)
what is the paramID in my case, Clear and appropriate answers would be very helpful and thanks in advance.
Message Edited by Pavan K on 07-11-2009 12:38 AM

I have made a program with LabVIEW 5.1 based on NI 6602, in which four counters were used.
Counter 3 is used to generate pulses, which are directed to the gates of counter 0, 1 and 2.
The source terminals of counter 0,1 and 2 receive pulses, individually, to count how many pulses appear during the time interval of each gate pulse.
The results are stored in a data file.
In order to test its performance, only one signal of ramdom pulses is sent to counter 0,1 and 2.
But I find that at the beginning the counts for the three counters are the same, but the following counts are totally different!
What's wrong? And how to solve such a problem? Does it have something related with synchronization?
Thank you very much!

Ep 630, 1 ear has higher frequency range??? why?

Well it just happend one day one ear the ear with the longer cord now has a higher frequency rance than the other or maby the other has a smaller one i have not treated it bad not put it in water or annything i use with my zen vision m so it should not overpower and break it and my zen is on bass boost and smart?volume?but when i turn?those off it is still stuffed (unequal) and i dont have anny settings like eq on they are off,?the only thing that i do with them is use them with my zen v m but i do wrap them around my mp3 them put it in my pocket but is that anny diffrent than scrunching them up and putting them in my pocket,?i dont jump armound and fall over on to my mp3 at all, just sit's nicely in my pocket why is it bad?it's not my zvm because i pluged it in to my computer and they were uneven?i'm not happy i love these in- ear headphones but why do theu have to stuff up? why?please help me or i will not buy creative headphones again!!!

Hi,
I am sorry but you probably need to contact customer support about this.

FP-CTR-500 and Frequency Measurement: How to modify it to report the frequency (0-10 Hz) every one minute?

How to modify "Frequency Measurement" to report the frequency every one minute?
The signal frequencies vary from 0 to 10 Hz (see the analog output plot and attached sample data file), so I want record the average frequency every one minute.
Software: Labview 8.5
Hardware: FP-CTR-500
Program: "Frequency Measurement" --build in and under "NI example finder", It was attached with this message.
Physical wiring: (1) The signal I want to measure to count input 1 (pins 2 and 18). it is a pulse signal (range from 0 to 1 V, see the plot and attached data file).
(2) Wire Output 0 (pin 130 to gate 0 (pin 9). Do com pins 26 and 30 need to wire together?
FP-CTR-5000 was set up in Max based on the program instructions. I have tried different gating pulse frequency, my readings are always "0".
Attachments:
H2O_20130809.xlsx ‏18 KB
Frequency Measurement.vi ‏35 KB

CTR-500 high pulse is >=10V. Hence, it always read your pulse as low. With this low voltage pulse, you must use analog input module, and write a program to read pulse from analog level. You must also make sure that you pulse is not so narrow that cFP loop is not fast enough to capture voltage change.

High frequency quadrature decoder (NI PCI 6221)

Hello, i would like to ask you about high frequency quadrature decoder. I am using module in DAQmx for measuring linear position. For this i am using NI PCI 6221. My problem is that i want to use this for my interferometer and we need really high speed. So I tried to use External timing whitch should be possible for this card up to 80MHz. Unfortunatelly i always will get error message that there is some kind of owerflow and my program crashes. So my question is how to get all data form this card. I know that the buffer size FIFO is only 2 so if it is impossible to get all data so i want find another solution. Is it possible let my card work alone on 80MHz and only repeatly rewrite all buffer and just sometime ask this card for sending current buffer. I dont really need all the data, but when i will ask i need to know reall position. This high speed is really necessary because my interferometer is sensitive and i dont wat to lose any steps. If there would be any possibility how to work on 80MHz and only sometime ask for sending data with position, it would be great. Sometimes i will ask not for only current position but for full buffer because i want so see what is happening during some time period, but this task will be only sometime.

Dear BMAJTZ,
The counter frequency (the maximum speed available) is configured by the Task in the background. In our case, the counter is set to detect edges, so it always uses the maximum speed available. If an edge occurs, the count value increases by 1, and this accumulated count value (stored as a binary number) is read by the DAQmx Read VI, and converted to meters. So if your encoder input is slow enough for the 80 MHz card to handle, you won't miss any ticks, even if you only read the value occasionally.
You can find further information about counters and encoders on these links:
http://www.ni.com/academic/students/learnlabview/digital.htm
http://www.ni.com/white-paper/7109/en
Also if you can tell me the approximate frequency of your encoder signal, and how often you nedd the position info, I can do some benchmarking for you to see if your card is capable of the task.
Best regards:
Andrew Valko
National Instruments
Andrew Valko
National Instruments Hungary

Can I measure AC voltage using FP-AI-102? I want to measure in the range of 0-120 VAC

Can I measure AC voltage using FP-AI-102? I want to measure in the range of 0-120 VAC

Hello Luis,
The update rate on the AI-102 module is 360Hz, which means that you can only accurately acquire waveforms with frequencies below 180Hz.
FieldPoint wasn't made for high speed measurements, so you will have to make sure that you are able to acquire the waveform you want to with the hardware that you have.
If you want to know how you would do the acquisition, I urge you to take a look at the LabVIEW shipping examples.
Help»Find Examples... and browse to Hardware Input and Output»FieldPoint»Analog IO
As for writing to the file, you can take a look at examples under Fundamentals»File Input and Output. You can use the functions included in the Functions Palette under Programming»File I/O.
I hope that this helps!
Kameralina
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NI9411 wrong frequency measurement of flow sensors / 24 impulse signals

Hello Ni Forum,
I already searched for similar problems, but haven't found anything helpful. So I'm posting our problem here. I'm apologizing in advance for bad english, it's not my mother tongue
We're encountering some strange behaviour of our NI9411 Module. We're using it in a Compact Rio with some other modules (2x Analog In).
Our goal is to measure the frequency of three flow sensors (impulse high = 24V, 0-22kHz) among with a torque sensor (TTL 5V, 30-60kHz) and a speed sensor (TTL 5V, 0-51,2kHz).
They are wired as follows:
DI0a = torque sensor
DI1a = flow sensor 1
DI2a = speed sensor channel A
DI3a = speed sensor channel B
DI4a = flow sensor 2
DI5a = flow sensor 3
Correspondig ports b are left unconnected, as it is said in the data sheet. All ground ports of sensors are connected to COM port of 9411. The module was connected to a 24V power supply.
Now the torque and speed sensor measurement works fine. But measuring the signals of the flow sensors seems to be difficult.
If an external frequency generator (impulse high about 9V, f=1,000kHz) is connected to port DI1a instead of the sensor signal, LabView shows exactly 1,000kHz. DI5a showed an avarage of 10 Hz, with a range from 10 to 60 Hz. DI4a equaled constant zero. The flickering up to 60Hz of DI5a was gone after disconnecting the 24V supply of the module. This changed nothing on the phenomenon described below.
If the signal high impulse voltage is raised, the measured signal frequency goes up to 1300 Hz @ 24V signal high impulse voltage. The signal additionally raises, if an oscilloscope is connected to DI1a, to 2180 Hz (range 2110 to 2240Hz). However, there is no change of frequency if the osci is connected to DI5a. With the 24V supply connected, DI5a showed a frequency up to 600Hz @ 24V signal high impulse voltage on DI1a, also rising when connecting the osci on DI1a. As mentioned, there was no frequency measured on DI5a after disconnecting the 24V power supply.
The signals of the generator showed some peaks on each edge (rising and falling) with values for example of 11V above high impuls voltage of 9V (20V together). That may causes that wrong frequency measurement.
The signals of the flow sensors do not have such peaks, the LabView-frequency nevertheless does not match the real frequency, as shown below (all values in Hz):
LabView
ideal values
Flow Sensor 1
Flow Sensor 2
Flow Sensor 1
Flow Sensor 2
4600
12200
740,6
6760,0
6400
13500
1481,3
7500,7
9700
16400
2962,6
8982,0
12900
19500
4443,8
10463,2
We're kind of helpless now. How can we get the signals of the flow sensors measured the right way? Are we doing something essentially wrong? Thanks in advance for offered help. I hope, I've given any necessary information. Any missing details will of course be delivered.
Puls-Measure-VI is attached beneath.
Regards,
Johannes Rost
Attachments:
vi.png ‏20 KB

Dear Lynn,
thank you for your reply. The impedance was an issue that our local technical distributor already suggested to check. According to the datasheet of the flow sensor (see attachement) it can drive a current of 25mA. The signal generator we used is a test generator that can be used instead of the flow sensors to check the any evaluation unit the sensor is connected with. So it should generate signals that are equal to those the sensor would have generated. And even with this the frequencies measured with LabVIEW are not as expected.
We are in contact with the sensor manufacturer to exclude mistakes in connection on the sensor side. But the behavior with the signal generator makes us think that is has to do something with the characteristics of the NI9411 that we don't know yet.
Attachments:
block diagram signal amplifier and signal description.png ‏151 KB
technical data.png ‏124 KB

Daq 6211 high frequency ouput

HI guys.
Ive got my hands on a USB 6211 daq device. Im trying to generate a high frequency pulse output from one of the 2 counters. The frequency is in the range of 5 to 20 kHz. Can someone tell me if thats possible with this USB 6211 device?. Ive been searching but cant seem to find the answers. Are the counters on this device just for reading HIgh Frequency inputs or can they ouput them also. Any help would be much appreciated.
Solved!
Go to Solution.

That manual has helped a lot. I should have looked at properly in the first place. Thanks .
I have one more question if anybody can help. I'm using the daq 6211 to create a pulse train to control a stepper. The stepper driver takes in a pulse which in turn will turn the stepper and the frequency of these pulses determines the speed.
My problem is that, using the counter examples in labview, I only have an option to create a continous pulse train. I would like top be able to dynamically adjust the frequency while the vi is running and Ideally i want to be able to ramp up the frequency so that the stepper can get to a high speed. If i try to adjust the controls with the example vi's there is no change in frequency unless i stop it and start again with a different frequency.
Has anyone come accross this themselves or am i missing something obvious??.

Frequency measurement of a very short pulse

Hi I am using PXIe 6368 to measure Oscilliator Frequency. This signal is connected to PFI lines and I would like to use counters to measure frequency but the pulse width is too brief ( 12 ns ) . How can I determine if the hardware counter can even detect this short pulse for frequency measurement?
Thanks

Gerd,
i am not aware that TTL specifies detailed timing information. The main reason: TTL was introduced as "standard" in 1961. In the mean time, all our semicondictors are way faster than back in that time. So if TTL would specify timing in detail, there would be the requirement for different versions of TTL (just like USB 2.0 vs. USB 3.0).
I don't know about TTL 2.0 (or higher), so i doubt timing specs to include hard numbers.
NI specified TTL signals for older controller chips (compare here) but i am not aware of any updated document for STC3 chips which are used for X-series devices.
Norbert
CEO: What exactly is stopping us from doing this?
Expert: Geometry
Marketing Manager: Just ignore it.

High frequency measurement 2 counters range

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