Highpass filtering for counter input signal

Hello,
I need to use high pass filter for my counter input pulsewidth measurement.
I can do offline filtering on stored pulsewidth signal.
I want to do same thing online.
Is there any way to do it?
I am using pci 6220 for counter input for pulsewidth measurement.
Thanks
Nisarg Shah

Hi Nisarg,
This response is pretty late but have you seen any of the Filter VIs in LabVIEW? Can you apply a filter to your signal with these?
If this does not address your question, please provide some more information regarding your application, what you want to achieve and what you've tried.
-Cindy

Similar Messages

6251 Counter input signal

Hello,
I am acquiring pulses which are 0-5V with the counter of the PXI 6251. However, I would like to know if it is possible to acquire pulses that are, for example 0-12V or 0-24V without damage the device. In other words, which is the voltage range for the counter input in a PXI 6251?
thanking in advance,
CJMV

Hi,
You will not be able to use the counter directly but you can setup an analog level trigger for your signals. This will create a pulse that isTTL compatible for you everytime the signal crosses a particular level. Then you can route this into your counter and perform any counter measurements on it. An example is this is shown here where it sets up a level trigger to make frequency measurements.
Alternatively you can purchase an industrial strength digital I/O board such as the USB-6525 but this does not include a counter.
Please let me know if this works out for you.
Message Edited by Abhinav T on 07-06-2007 05:20 AM
Abhinav T.
Applications Engineering
National Instruments India
LabVIEW Introduction Course - Six Hours
Getting Started with NI-DAQmx
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Custom scale for counter input?

Hello everyone,
Is it possible to create a custom scale for a counter input? I saw there is a feature to allow input Custom Scale Name to the Channel Property Node. However, when I tried to create a custom scale to input to the channel, I got this error
Error -200212 occurred at DAQmx Read (Counter DBL 1Chan 1Samp).vi:1
Property: CI.MeasType
Corresponding Value: Count Edges
Property: CI.AngEncoder.Units
Corresponding Value: From Custom Scale
Channel Name: CountEdges
Task Name: MyCountEdgesTask
Do you know what is the problem with it? Thank you

How do you have the channel set up? Can you attache the VI's that you are using? Is this a global virtual channel?
Tim
Johnson Controls
Holland Michigan

Route multiple 6602 counter inputs to one counter output...

Hi!
I´d like to route 4 different ttl signals, that are read by 4 different counter inputs to one single output channel (e.g. the output of one of the counters used) using pulse train generation with a divider of 4. Note that only one of the four inputs is active at the same time, to prevent overlay.
How can I do that with Traditional-DAQ?
Setup would look like this on the SCB-68
TTL1 ----o in0 (ct0)----o out0 TTL(1..4)/4 [Hz]
|
TTL2 ----o in1 -- (output of ct2 is redirected ro ct1)
|
TTL3 ----o in2 --
|
TTL4 ----o in3 (ct3)--
May it be better to just output each counter input signal at it´s own output and connect these outputs to one free I/O-pin hardwired?
Best regards
Zorniki

In the end I configured a counter for Pulse Train generation and opted to change the duty cycle and frequency via 'DAQmxWriteCtrFreqScalar" (i.e. Pulse Width Modulation)
I registered a callback for the 'DAQmx_Val_CounterOutputEvent' and then changed the dutycycle and frequency in that callback.
Unfortunately, I kept getting "The pulse generation with previous property settings must complete a
full cycle before the property can be updated." error messages and, opon further reading, managed to find a doc where National Instruments suggest adding a 'Wait(period)' before executing the 'DAQmxWriteCtrFreqScalar' call.
The problem with this solution is that it one has to wait a minimum of 2 Periods before the Pulse Train can be modified which is not acceptable for our work.
So is there an alternative solution which allows us to change the Pulse Train after only 1 Period ? Is there an event we can trap which allows us alter the Pulse Train after every period ? I'm sure PWM must be possible on Daq cards (PCI-6602 or PCI-6281 or PCI-6259)?
Cheers, Shaun.

Display FFT of input signal which receive from VISA read ?

Hi.
I receive data from MCU whcih sampling frequency is constant and we assumed it is S. now I get data from MCU with using VISA read block. I can display data, perform some functios like filtering, multiply and save them in txt files. all thing is OK.
but when I want to see FFT of incomig data on chart , it doesn't work !! I use this VI for calculate and display FFT of input signal (from VISA read) and display it which in Y-Axis is magnitude and X-Axis is frequency.
in your mind why this is not work and what I must done for show input signal FFT and frequency components ?
Thanks.

If I understood this correctly, you are getting the correct results when outputting to a text file but you are not able to see the results when trying to output to a chart?
This discussion may be of some help to you.
Rob S
Applications Engineer
National Instruments

Counter Output/Counter Input PXI Signals Behaving Erratically

Question for all your LabVIEW guru's out there,
I am running a frequency loopback test using the NI PXI 6229 MIO DAQ card. I am generating a "Counter Output" pulse train signal which feeds through my device under test and then back out of my device under test and back into the PXI 6229 for a "Counter Input" frequency measurement. Both the "Counter Output" and the "Counter Input" are assigned different PFI lines using DAQmx in LabVIEW.
I have 4 lines to test on my DUT. All four lines run this same frequency measurement but with different PFI lines on the PXI 6229. Each line is test independently.
This is my setup for the 4 lines:
Path 1: P2.0 (Counter Output - Pulse Train) -> DUT (Device Under Test) -> P2.1 (Counter Input - Frequency Measurement)
Path 2: P2.2 (Counter Output - Pulse Train) -> DUT (Device Under Test) -> P2.3 (Counter Input - Frequency Measurement)
Path 3: P2.4 (Counter Output - Pulse Train) -> DUT (Device Under Test) -> P2.5 (Counter Input - Frequency Measurement)
Path 4: P2.6 (Counter Output - Pulse Train) -> DUT (Device Under Test) -> P2.7 (Counter Input - Frequency Measurement)
where:
P2.0 = PFI8
P2.1 = PFI9
P2.2 = PFI10
P2.3 = PFI11
P2.4 = PFI12
P2.5 = PFI13
P2.6 = PFI14
P2.7 = PFI15
I have a LabVIEW VI which generates the "Counter Output" and reads the "Counter Input" frequency. I am seeing weird behavior from the PXI 6229 card. I can test "Path 1" and "Path 2" and the frequency I read is what I generated. No issue there. However, when I test "Path 3" and "Path 4" the frequency measurement is erratic. The readings are two different frequencies repeated over and over again and none of those frequencies are the expected frequency which was generated out of the "Counter Output." If I reset the card, and start by testing "Path 3" and "Path 4" the frequency readings are correct and the erratic behavior is gone. However, when I try to then test "Path 2" and "Path 1" now those lines have the erratic frequency issue. I can continue resetting the card and see same issue. The PFI lines that I test first will always pass.
To summarize:
Steps Taken:
1. Test Path 1 = SUCCESS
2. Test Path 2 = SUCCESS
3. Test Path 3 = Erratic Frequency (Two Frequencies repeated over and over again in my frequency results array)
4. Test Path 4 = Erratic Frequency (Two Frequencies repeated over and over again in my frequency results array)
5. Reset the PXI 6229 Card
6. Test Path 3 = SUCCESS
7. Test Path 4 = SUCCESS
8. Test Path 3 = Erratic Frequency (Two Frequencies repeated over and over again in my frequency results array)
9. Test Path 4 = Erratic Frequency (Two Frequencies repeated over and over again in my frequency results array)
I am wondering if Port 2 (P2.0-P2.7) on the 6229 card has certain dependecies and this is why I am seeing issues. I am trying to get around this issue so that I don't have to always reset the card.
Are P2.0-P2.3 (PFI8-PFI11) and P2.4-P2.7 (PFI12-PFI15) treated differently or require different setup? How do I resolve this issue?
Thanks so much!

I have a theory...
The DAQ card follows a policy called "lazy uncommit" wherein the terminal used for the output will continue to be connected to the counter even after the task has completed (until the terminal is needed for something else). So as you run more tests, the counter output will end up driving more lines. This behavior should be easy enough to confirm.
As the DAQ card drives more lines, I'd imagine this affects the actual signal. You could scope it to check, but it sounds like either the rise/fall times are becoming longer or some extra noise is being introduced on the line.
The readings are two different frequencies repeated over and over again and none of those frequencies are the expected frequency which was generated out of the "Counter Output."
This implies you are picking up an extra edge during transitions--this isn't too uncommon if the signal is noisy since there is no built-in hysteresis on the DAQ card. I would expect the measured frequencies to have periods that sum to either the full period or the semi-period of your actual signal (depending on how many duplicate edges are detected).
Suggestions are as follows:
To stop the DAQ card from driving multiple PFI lines, it would probably be easiest to just programmatically reset the device in between your tests (using DAQmx Reset Device). If you can't reset the device (e.g. because you are running some other task that can't be interrupted) then you can instead configure a dummy task that uses the PFI line in question as an input.
To stop the DAQ card from picking up multiple edges during transitions, you should configure a digital filter on the input terminals. If you reset the device it sounds like this might not be necessary... it's up to you if you want to configure this or not.
Best Regards,
John Passiak

Graphing Encoder Counter Input in LabVIEW Signal Express

In LabVIEW SignalExpress, using a simulated daq system with a counter input, I set up a DAQmx Acquire of an Angular measurement based on a quadrature encoder. Acquiring N samples, I acquired a table of measured values. I would like to plot the results, however, I am not given the option to view the data in any other format. I can plot if I acquire one sample, but that does not allow me to sync the data with the analog input signal I would also like to acquire and view. I had to use an external clock to take the encoder data, so the data is acquired a double datatype. I would like to be able to view in realtime, encoder position with respect to time.

HI,
I want to obtain of this combination of hardware and software a system that allow me acquire a signal of the load cell and the counts of the incremental encoder’s pulses and represent in a graphic the force vs the distance.
The distance is pick up to a incremental encoder in a worm gear that with its movement, move a load cell in a base. the reading of the position is in millimeters.
In this moment, I can only represent the force, the position is only visible in a display, I want to take a samples of the force and the count in millimeters, ten or more times per second and perform a graphic in a real time.
Thank you for your answer
Best regards
Lizardo Laguna

4 counter input & 6 signal input HELP

Hello Friends,
I have a little problem, would be great if someone can help me.
I am using the counter inputs on my Data Acq. Harware to measure the pulse width of my input sigal.
Since the hardware has only 4 counter inputs I can connect 4 channels, but I want to measure pulse width for 6 channels.
Is there a way to use the available 4 counters and measure all of the 6 channels?
Thank you
Regards,
Raj
Solved!
Go to Solution.

In my (very basic) example, you could just increase the timeout to ~10+ seconds to ensure you acquire the pulse. If it's possible that the pulse isn't present within the ~10+ second timeout you would also need to handle the timeout error so it doesn't wrap back around through the shift register and prevent the future reads from executing.
The downside to this of course is that it could take up to ~60+ seconds to acquire from all 6 channels in the worst case scenario. The example was really just intended to show how one might use a single counter to acquire from multiple channels in succession.
The better way to do it with counters would be to run (up to) 4 counter tasks in parallel. The first 2 tasks to finish with their original acquisition should then measure a second channel. This could still take ~20 seconds if none of the signals are connected however.
If you want to trade a lower measurement resolution (and more memory usage) for a lower upper-bound on measurement time you could instead acquire a 10 second window of time using clocked digital inputs and use software to determine the pulse duration by parsing the acquired array.
Best Regards,
John Passiak

Developed VI for data input from a Serial RS485 S. Himmelstein 700 Series Signal Conditioner

Has any one developed a VI for data input from a serial RS485 connection with S. Himmelstein 700 series signal conditioner. Multiple displays and channels. Labview 2009

Hi
I am using the same vi which you have suggested and i have selected proper com port and other settings, but i am not getting any data,but if i send "ADC0" and "*IDN?\n" command alternatively then it is giving the data...but if i do that i will get zero and data alternatively.I want to get data without zero in between.. any solutions on why i have to send *IDN?\n?
Expand.Evolve.Influence
Attachments:
Hammltn.jpg ‏91 KB

Is it save to use digital output as a digital input signal for another channel

Hi all,
I know this is a stupid question, but I do not have other signal generator by hand. So what I want to know is, can I use the digital output signal of my USB-6001 as an input signal for the same device but on other digital port? I did not try out directly because I do not want to burn the device down......
Thanks
Solved!
Go to Solution.

I do loop backs all the time, especially in my test systems as a way of making sure my signal is making it to the UUT pin. I typically throw in a 10k resistor just in case, but I have never had an issue.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

Benchmarks for Buffered Counter Input with X-Series Devices

Hi,
Does anyone know the maximum transfer rate (using dma) for the x-series cards?
I'm looking for data simillar to the one in this link:
http://digital.ni.com/public.nsf/allkb/72A7E41EE5A8756A862571DA0076F1D7?OpenDocument
More specifically I want to know the transfer rate for the PCIe 6343.
Thank you,
Eyal
Solved!
Go to Solution.

I benchmarked 8MS/s on a single channel on a USB-6353 (should have similar performance to the USB-6356/66) with a buffered counter input task. This was only a 10 minute test on my Dell E6400 laptop ( Windows 7 32 bit, Dual core P8600, 4GB memory) so a sustained 24/7 rate is likely less. Also, I wasn't doing much with the data, just displaying it in an array. This is pretty much topping out USB streaming on this system (32MB/s) so I wouldn't expect to get higher. I wasn't running much else in the back ground (Explorer, Powerpoint, Lotus Notes) and CPU was at ~20%.
Hope this helps,
Andrew S
Getting Started with NI-DAQmx
Measurement Fundamentals

What is the power spectrum unit for Unevenly Sampled Signal Spectrum.vi if the input signal unit is Volts?

The Unevenly Sampled Signal Spectrum.vi has two outputs, Power Spectrum FFT(X) and Power Spectrum FFT(X) Frequency. Can anyone tell me what's the unit for Power Spectrum FFT(X) if the input signal unit is volts. Also, is this VI equivalent to producing a PSD output?

Hi,
The power spectrum will be in units of Vrms^2 which are power units. There is a very usefull VI that you can use to easily transform the units of your spectrum; the VI is called Spectrum Unit Conversion.vi. You select the type of spectrum that you have and the units that you want it to be converted to.
Here is a good document on spectral measurements in genereal:
frequency spectrum
I hope this helps.
Regards,
Juan Carlos
N.I.

Could i use MyDaq to catch 4 pwm input signals which for controlling Stepping Motor?

Dear,
I got 4 Pwm input like picture below.
I try digital count, also digital input with timestamp but not be able to catch them correctly.
Is there any possible solution for this problem?
Thanks alot.

Hi there,
If you want to do the edge counting for any purpose
You can try with DAQ assisant function and setting the Counter Input section as Edge Counting
Or with the more flexible DAQmx API:
Are you going to measure the digital count for 4 Axes sepearately? Because there's only one counter available on MyDAQ device:
http://www.ni.com/pdf/manuals/373060e.pdf

Difference between USB6008 &USB6215 counter input?

Hello,
I have to count pulses of a gas meter (5029 pulses = 1 m3 gas).
I did this with a USB-6008 and it works OK. Now I want to switch over to USB-6215 and counting goes wrong.
The USB-6215 counts one cycle random a lot of pulses (e.g. 250) and next cycle 1 as it should be if I select rising edge. This alternating process goes on and on. If I select falling edge then every cycle it counts a lot of pulses more.
I have the inputs connected parallel so both modules have exact the same pulses. Pulses are 4,7V with low frequency 1 Hz till max 100 Hz.
USB6008 input in connection = pin 29 (pulse) & pin 32 (gnd)
USB6215 input in connection = pin 1 (pulse) & pin 5 (gnd)
In the MAX same result as with attached LabVIEW program with rising edgge selected.
Who can help me?
Rgds Geert
Attachments:
gasmeter.vi ‏19 KB

Hello Martijn,
Thanks, yes this works! With digital filtering set on 2,56ms I get with USB6215 same counting as with USB6008.
If I put digital filtering on 6,425 us then sometimes I count too much, at 125 ns this happens regularly but much less then without digital filtering. These are the only allowable settings, on other setting the counter does not work.
Has the USB6008 a standard filter then? With a scope on the pulse input signal I cannot find glitches, so it is for me still a question why a cheap USB6008 performs in this case much more user friendly.
Regards,
Geert Wever
Application Engineer
Honeywell Emmen NL

FP-CTR-500 don't read external count inputs

I have 4 frequency signal inputs (0-10 KHz) connected to ports 2,3,4,5 of one FP-CTR-500, but I can't read any change on counting values, using FieldPoint Explorer. The module is OK, all the LEDs are green, including those four inputs, the firmware version of FP-1600 is 4.11 and software version of FieldPoint Explorer is 3.0.0 I can view a fix value of 53xx counts on each input, after a power up sequence (the external frequency is 8.2 KHz aprox.). What can I do?

There are several reasons that you may be having problems with the count. First, if the channel LED is always on, then the signal wired into the FP-CTR-500 may not be going low enough (below 6 volts) for the module to see the falling and rising edges. Second, if the inputs have been configured with the 200 Hz low pass filter setting, you may be filtering out your signal. Third, if you have configured the count channels for internal count inputs (1 kHz Reference or 32 kHz Reference) or previous count channel, then the module is not looking at your actual wired signals. Fourth, If you have enabled the Gate Inputs (channels 8-11) for any of the counters, then the count will not increment while the gate is low. Fifth, if the channel is configured for Reset On Read fu
nctionality, every time the FP-1600 polls the FP-CTR-500, the channel will reset itself.
Regards,
Aaron

Highpass filtering for counter input signal

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