NI 6602 buffered pulse width and buffered period measurement with 2 counters synchronized during a defined time "

it is OK for 2 counters if I count a defined number but I would like the values during a time for example 10 s .It seems that the acquisition is not complete.Is a problem of circular buffer, time out error .....?

Hi:
I am assuming that you are using 2 counters to generate a finite pulse train for 10 seconds and are using this pulse train to gate the other counter. If this is your setup, you should not have a problem in retrieving the correct number of readings.
You can monitor to the backlog and number read by wiring indicators to Read Buffer VI. Please also look at the Count Buffered Edges (DAQ-TIO).vi examples to learn how you can correctly set up a buffered counter acquisition.
To open up the example, click on Help -> Find Examples -> Hardware Input & Output -> Traditional DAQ -> Counter -> NI-TIO.
Regards,
Bharat Sandhu
Applications Engineer
National Instruments
Penny

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NI 6602 buffered pulse width and buffered period measurement with 2 counters synchronized

I modify the example buffered event counting with 8 counters for use with 2.I obtain error 10600 or 10455 and never the waited values.Can you give me a VI example . Thank you for your help

What changes did you make to the VI? If you attached the altered example I could take a look at it. The example program for using 8 counters performs some configuration that you won't need for just two counters. For instance, if you just want to use counters 0 and 1, you won't need to perform pad synchronization.
I've altered the program to use with two counters and attached it to this response. Hopefully this will work for you.
Regards,
Todd D.
NI Applications Engineer
Attachments:
Buffered_Event_Counting_(2).vi ‏126 KB

Video pulse(width and count) train measurements

We need to measure the sync pulse's width in a video signal to first determine the occurrence of the vertical sync pulse in each field, and then we need to count the successive horizontal sync pulse edges in order to arrive at a specific video line.
Are there better suggestions on how to arrive at a particular video line in the video signal?

Do you want to do image acqusition and acquire the image from your camera for display/analysis purposes or do you just want to measure the distances between pulses. If you do want to acquire your images from the camera, you won't need to worry about measuring the distances, the driver will take care of all these details and just return the pixel values to you that occured during the active time of VSYNC and HSYNC on the edge of the clock.
If you do want to measure the timing of your HSYNC/VSYNC/pixel clock, etc. I would recommend a 6602 counter timer board. The DAQ people can give you more info on this.
Hope this helps,
Brad Buchanan
Image Acquisition
National Instruments

-10920 error when executing buffered period measurements on a PCI 6602 timer.

I frequently encounter the -10920 NI-DAQ error when I run the C code for single buffered data period measurement .
The error message is "One or more data points may have been lost during buffered period measurements due to speed limitations of the system". I am unable to resolve this error. I have a Win2K environment and am using VC++ to compile and execute the code. Please help.

When doing buffered period measurements, the rate at which you can transfer data from the counter is system dependant. To try to get around this there are two things you can try. The first is to set the 'number of counts to read at a time' to a greater number. This way, the 6602 board will use less calls across the PCI bus. If possible, try to limit the number of pulses coming in on the gate that you are using to latch the counts, though in many applications this is not possible.
Make sure that you minimize the PCI bus activity on your computer. This includes, video activity and any network activity along with anything else that is connected to the PCI bus.
Brian

Doing Data acq. and buffered period measurement using counters simultaneously, gives an buffer overflow error

Iam doing Data acquisition using NI-PXI 4472 and buffered period Measurement using NI-PXI 6602 simultaneously,my program gives an buffer overflow error

murali_vml,
There are two common buffer overflow and overwrite errors.
Overflow error -10845 occurs when the NI-DAQ driver cannot read data from the DAQ device's FIFO buffer fast enough to keep up with the acquired data as it flows to the buffer (i.e., the FIFO buffer overflows before all the original data can be read from it). This is usually due to limitations of your computer system, most commonly the result of slow processor speeds (< 200 MHz) in conjunction with PCMCIA DAQ boards, which have small FIFO buffers (e.g., the DAQCard-500). Sometimes using a DAQCard with a larger FIFO can solve the problem, but a better solution is to lower the acquisition rate or move to a faster system. Another cause of the -10845 error could be due to an interrupt-driven
acquisition. For example, PCMCIA bus does not support Direct Memory Access (DMA). If the system is tied up processing another interrupt (like performing a screen refresh or responding to a mouse movement) when it is time to move data from the board, then that data may get overwritten.
Overwrite error -10846 occurs when the data in the software buffer that you created for an analog input operation gets overwritten by new data before you can retrieve the existing data from the buffer. This problem can be solved by adjusting the parameters of your data acquisition, such as the lowering the scan rate, increasing the buffer size, and/or increasing the number of scans to read from the buffer on each buffer read. Additionally, performing less processing in the loop can help avoid the -10846 error.
See the NI-DAQ Function Reference Manual for a listing of all NI-DAQ error codes.
Have a great day.

Measure Pulse Width and Period Statistics

Hello,
I'm trying to solve what should be a very simple problem. I would like to measure common characteristics of a binary analog voltage input, pulse width and period. The canned pulse width/duty cycle/period VIs and express VIs use a histogram or peak to peak method on a set buffer size of data and produce one output. I would like to measure these signal characteristics over a long period of time and collect statistics on pulse width and period data (max, min, median, mean, standard deviation, etc.) to indirectly measure the eccentricity of a system. Although I am relatively inexperienced in LabView scraping off a considerable bit of rust, I did not think this task would present a challenge, but I have been stumbling around for a couple of days trying to create an array of output parameters such as pulse width so that I may calculate the statistics on all measurements.
If anyone can step me through some of the thought process to a solution or show me how to format data collection so that this can be done, I would very much appreciate the help.
Thanks,
Evan
Attachments:
Example.jpg ‏194 KB

Hi Gena,
I am assuming you are using the DAQmx drivers in LabVIEW for your
PCI-6014. Avoiding a While loop may be difficult if you need to
perform this measurement many times and you might not know when the
signal is going to begin. Without a While loop, you'll have to
set up your timeout period long enough so the pulses will begin before
your VI stops.
With this in mind, you may want to look at some of the shipping
examples with the DAQmx driver. You can find these in LabVIEW's
Help menu by going to Find Examples. For measuring the pulse
width, browse the folders in the Example finder by going to Hardware
Input and Output>>DAQmx>>Counter Measurements>>Period
or Pulse Width. In this folder, there is the Meas Pulse Width.vi,
which measures the pulse width once and stops. You should be able
to take the pulse width measurement you get from here and check to see
if it's in your range, then output a pulse on the other counter if it
is in the range. The pulse output examples can be found in
Hardware Input and Output>>DAQmx>>Generating Digital
Pulses>>Gen Dig Pulse.vi.
Thaison V
Applications Engineer
National Instruments

What is the min pulse width that can be measured using a 32-bit conter?

what is the min pulse width that can be measured using a 32-bit conter?
and also by chnaging the referenced Clock, can we measure as min as 10ns pulse width?

You could measure a 40ns pulse, but not with a great degree of accuracy. Here's a good document on how counter pulse width measurements are handled:
http://zone.ni.com/devzone/conceptd.nsf/webmain/7C77FB9EDC17C3C386256802007B8AB3
With a 40 ns pulse, you'd have 3 counts per pulse so your uncertainty is pretty high (33%). Another way to look at it would be that you would read either 3 counts or 4 counts which would be values of 37.5ns (3*12.5ns) or 50ns depending on where the rising edges fall. So you wouldn't be able to tell the difference between a 40ns pulse and a 42ns pulse, but you would between a 40ns and a 100ns.
Hope this helps,
Andrew S
National Instruments
Message Edited by stilly32 on 09-18-2006 05:04 PM
Getting Started with NI-DAQmx
Measurement Fundamentals

Measure pulse width and generate pulse depends on the width

Hi,
i have a serias of pulses ... 600 micro,30 micro,30 micro (around 10 times) ........ nothing for 1 mili second ..
so i need to generate a pulse after the first pulse arrives ... (its width around 600microSecond)
1. use the first counter to measure the pulses ...
2. if arrived pulse ... 500microSecond<the pulse width<700microSeconds .... then generate pulse with second timer ....
the problem is that i dont want to use the while loop inside the labview ...
can i programm the counters to make the width calculation and if the width is bigger to generate trigger to the second counter .... ?
the hardware is 6014 sample card ....
thanks
gena
(see attached)
Attachments:
F0087TEK.JPG ‏27 KB

Hi Gena,
I am assuming you are using the DAQmx drivers in LabVIEW for your
PCI-6014. Avoiding a While loop may be difficult if you need to
perform this measurement many times and you might not know when the
signal is going to begin. Without a While loop, you'll have to
set up your timeout period long enough so the pulses will begin before
your VI stops.
With this in mind, you may want to look at some of the shipping
examples with the DAQmx driver. You can find these in LabVIEW's
Help menu by going to Find Examples. For measuring the pulse
width, browse the folders in the Example finder by going to Hardware
Input and Output>>DAQmx>>Counter Measurements>>Period
or Pulse Width. In this folder, there is the Meas Pulse Width.vi,
which measures the pulse width once and stops. You should be able
to take the pulse width measurement you get from here and check to see
if it's in your range, then output a pulse on the other counter if it
is in the range. The pulse output examples can be found in
Hardware Input and Output>>DAQmx>>Generating Digital
Pulses>>Gen Dig Pulse.vi.
Thaison V
Applications Engineer
National Instruments

How to generate a pulse train with different pulse width and delay?

How to generate a triggered pulse train with different pulse width. for example, after each trigger signal, let's say 2 ms, then the counter output a pulse with pulsewidth of 1 ms, and then after 3 ms delay after the first pulse, the second pulse was generated with a pulse width of 4 ms. Next cycle when the trigger signal comes, the same two pulses will be generated and so on. Is it possible to achieve this by using 6601 counter card? and if yes, how to achieve this? Thanks!

Unfortunately you can not create a hardware timed pulse train with different widths on each pulse from a counter. Whilst it can be changed on the fly using software, since you require a hardware triggered signal getting the software involved will not give a huge amount of accuracy when the pulse will actually change.
So in short you can't use your 6601 card (or a counter timer) to achieve this
There are three possible Alternative solutions
1 You could use a high speed digital IO device such as the (6533/34) to generate your variable signal which would require setting up the pulse train as a series of states based around the burst transmission mode where the clock would give you your specific timing.
2 A timed analogy output (for example on a MIO card with a clock (PCI-6220 / 62xx), i.e. Not the 6704 style static analogy output cards)
3 A high speed digital waveform card such as the (, 656x , 655x, 654x, 6534, 6533 (http://www.ni.com/modularinstruments/find_right.htm) ) this could then be scripted to work with your triggering and also there is a digital waveform editor which will enable you to set up the pattern you wish to generate (http://sine.ni.com/nips/cds/view/p/lang/en/nid/13555)
Hope that helps
Tim Matthews
NI (UK)

Analog period measurament with ext. clock.

Can I measure a period of an analog signal (6052E w/ SC2345 accesory) with an external timebase (6602 w/ BNC2121). The devices are RITSI'ed together. I am trying to do this in DAQ mx.

The terminology between Traditional DAQ and DAQmx is quite a bit different as far as counters go. In DAQmx, the gate and source pins on the counter are no longer featured in the API. Instead, you either specify the source of the input signal, trigger, timebase, or clock that you want to use for your application, and the driver will automatically route the source to either the internal source or gate pin on the counter as appropriate. To see how the source and gate pins are used for different applications, look at the NI-DAQmx Help->Key NI-DAQmx Concepts->Counters->Counter Parts chapter. For example, if you want to use an external timebase for your counter, you will need to set the Counter Timebase Source attribute (Counter Input:General Properties:Counter Timebaseource) under the DAQmx Channel Property Node.

PCI-6602, How to convert Pulse Width to RPM and stop updating datalogging at 30 RPM

Hi all,
My objective is to stop updating data logging pulse width measurements at 30 RPM so I can record the time lenght it takes the RPMs to stop from 6000 to 30 RPM. When I turn off the tool. I have an encoder attached to an output shat of a 6000 RPM circular saw. I have created 3 program methods, but I was not able to stop at 30 RPM. The last pulse width value the data log updates is around 200 RPM. I don't know if I'm using the right method to read RPMs?
System:
1)     NI-PCI 6602 Counter/Timer Card
2)     SBC-60 Connector Block
3)     TRD-S1000-VD Encoder. 1000 PPR
4)     LabVIEW 8.5.1
5)     PC Dell Precision T3400 (32-bit), Intel Core Quad 2.4GHz, Memory 2GB. Windows XP prof.
In method 1: I reading pulse width and converted to RPM with this formula. RPM = 60/(1000 PPR/ Pulse Width).
In method 2: I just measuring pulse width and try to stop while loop when pulse width value is greater than 0.002 mSec. by using this formula 60sec/30rpm = 2 sec/rev, 1 Rev = 1000 counts. Therefore,     2 Sec / 1000 Counts = 2 mSec/Cnt (0.002)
In method 3: I measuring pulse width using this formula,                                                                   Pulse Width (in Sec) = Count/Counter Timebase Rate (20MHz), One period is 1000 cnts X 0.002mSec = 2. Therefore, Pulse Width = 2 / 20MGz = 0.000000100
All three methods stop recording pulses around 200 rpm. I wonder if the formulas I utilizing, are not using them properly. Or there is floating point number conversion???? Please See attached Picture.
Any help is greatly appreciated. THANKS!!!
Carlos G.

Charles_DeJesus,
Could you check the output waveform of the encoder? Do you see spikes? Sometimes spikes might produce wrong counts.
CarmenC

Sum low pulse width over fixed time period

Hello,
I'm using a NI cDAQ-9178 with the NI 9411 DI module. I'm looking to read a (not very clean) ~100kHz square wave
signal and sum the low pulse width (1-3us each) over a 5ms period. The falling transition is relatively clean, but
the rising transition is a bit slow (0.5-1us).
Any advice on how to code this? I've looked at the counter examples for measuring pulse width and semi-periods,
but the values I get with those examples do not match what I measure with an oscilloscope.
Thanks,
Anna Liao

Hi Anna
It does not sound like you are receiving any errors, but maybe the suggestion provided in the document I Get Error -10920 When Counting Square Waves without an Adequate Rise Time can help in your application. It sounds like it could explain why your values do not appear correct.
Milan

How can I configure the CTR 1 GATE to output a pulse (10us long) and then immediately take a pulse width measurement?

I'm using the BNC-2120 DAQ and LabVIEW for interfacing with an ultrasonic position sensor. The sensor is the "PING))) ultrasonic range finder." It measures the distance from PING))) to some object directly in front of it. It has 3 pins (5V, ground, and a signal pin). The 5V and ground are easily taken care of with the 5V and digital ground outputs on the DAQ. The signal (SIG) pin works in the following way:
1) Send a 10us, 5V pulse to SIG. This triggers PING))).
2) Wait 200us. PING))) takes a distance measurement.
3) SIG outputs a square wave with a specific pulse width.
The pulse width varies with the distance of the object away from PING))). I've tried using CTR 1 OUT to generate the pulse, and then using CTR 1 GATE to measure the pulse width. However, the measurement is stuck measuring 0V because CTR 1 OUT is on the same pin! So PING))) tries to output a pulse, but cannot due to the fact that CTR 1 OUT forces the SIG voltage to be 0V. So I need to use just one counter I/O line to trigger and measure. How can I do this?

Hi Matttastica,
What DAQ
card are you using? The reason I ask is that the PFI lines on some cards can be
used as PFI lines and digital I/O lines, while on others they can only be used
as PFI lines. The pinouts and diagrams for our cards can be found at www.ni.com/manuals. You can accomplish
what you are looking to do if your PFI line is a DIO lines as well.
I would
suggest doing two tasks, one for counter output and one for counter input.
(Note that both these are not going to be the same line). The counter output
will be used to do a single pulse generation, while the counter input will be
used to read back the period.
This will
work because, at first, we are going to route the line from the counter output
to the counter input line by using a ‘DAQmx connect terminals’ (basically
making the input line an output line for a moment). First, setup the tasks and
the DAQmx connect, start the tasks and have the counter output do a ‘wait until
done’ to ensure the pulse is sent. After this is done, do a DAQmx disconnect
terminals (turning the input back from an output to an input), and then do a
DAQmx read for your counter input (period measurement). You may look at the
shipping examples for pulse generation and period measurement in LabVIEW (Help »
Find Examples... » Search tab … search for examples)
One note is
that since this is software timed, it may not be fast enough to meet your 200us
timing. If this ends up being the case, please look at the 6552, as it can do
per clock cycle direction change very fast.
David L.
Systems Engineering
National Instruments

How to generate and output 3 TTL square waveforms with different pulse widths using counters of NI 6034E

Hello
I just have a few questions.
I am using the NI 6034E DAQ board in order to
generate simultaneouly 3 different TTL digital signals, with different
pulse width, and output these TTL signals to an external circuit that I
am using for this application.
The following pattern of the TTL pulses will look like this:
01010101 01010101
00110011 00110011
00001111 00001111
From
what I understand, I have to use the 2 counters, Ctr0 and Ctr1, to
generate the TTL pulses that I desire, because the DIO lines are
software timed only and I will not be able to produce a deterministic
output period using these DIO lines. Am I correct?    Also, do I have
to use a separate counter to generate a separate TTL digital pulse. I
need 3 different TTL pulses and there are only 2 counters for this DAQ
device. The three generated TTL signals will be feed to an external
circuit. Concerning the hardware connections for my application, I
assume that the generated TTL signals will be output from
GPCTR0_OUT(pin 2) for counter 0 and GPCTR1_OUT(pin 40) for counter 1
of the NI 6034E. Is this correct? Is there any way that these TTL
signals can be output from three DIO lines(DIO0...2).
Here is some code that I plan to use in order to do this:
#include <NIDAQmx.h>
static TaskHandle gTaskHandle = 0;
DAQmxCreateTask ("", &gTaskHandle);
DAQmxCreateCOPulseChanTime (gTaskHandle, "Dev1/ctr0", "", DAQmx_Val_Seconds, DAQmx_Val_Low, 1.0, 2.0, 2.0);
DAQmxCreateCOPulseChanTime (gTaskHandle, "Dev1/ctr1", "", DAQmx_Val_Seconds, DAQmx_Val_Low, 3.0, 4.0, 4.0);
DAQmxCreateCOPulseChanTime (gTaskHandle, "?????", "", DAQmx_Val_Seconds, DAQmx_Val_Low, 7.0, 8.0, 8.0);
DAQmxCfgImplicitTiming (gTaskHandle, DAQmx_Val_FiniteSamps, 5);
DAQmxStartTask (gTaskHandle);
DAQmxWaitUntilTaskDone(gTaskHandle)
DAQmxErrChk DAQmxStopTask(gTaskHandle)
DAQmxErrChk DAQmxClearTask(gTaskHandle)
I believe this code should generate the 3 TTL square waveforms that I want for my application.
Please provide me with some feedback. It would greatly be appreciated.
Thank You

Hi,
The NI 6034E is a multifuntion DAQ device, this means you have:
(2) counters
(8) DIO lines (software timed)
(16) AI, single ended
(0) Analog Output
You have a couple choices here:
   1. Software timed digital output of all three signals, max 1khz loop rate, non-deterministic.
   2. Hardware timed digital output of 2 signals, max 20Mhz.
   3. Hardware timed digital output of 2 signals and software timed digital output of 1 signal.
   4. Find another NI MIO board such as the NI 6251. This board will do 10Mhz pattern generation for (8) DIO lines.
For the hardware connection, you are correct, the output for the counters will be taken from pin 2 & pin 40. Here's the pinout for the NI 6034E for reference:
The output of the Counters can be routed to some of the PFI's or to the RTSI connector. You can see this in MAX
Message Edited by Matthew W on 11-19-2007 01:24 PM
Attachments:
2007-11-19_131609.jpg ‏61 KB
2007-11-19_132435.jpg ‏86 KB

Measuring puls width and time of 5 signals

Hello,
I have 5 signal lines that generate different pulses in time. I need to measure the pulse width on every line but also the exact time when the pulse occurs on each line.
I have a PCI-6602 that I can use for this.
Measuring the pulse width is not that difficult. I wanted to use a buffered pulse width measurement using 5 of the counters of my PCI-6602.
But I do not know how I can also get the exact time for these 5 channels ???
Any ideas how I can accomplish this with my PCI-6602?
Note: I do not need to use the maximum source frequency for my counters. Measuring the pulses with a timebase of 1Mhz is enough. (maybe even 100 kHz but I need to do some more experiments to be sure).
Thanks in advance for all your help!

Only have time to outline some suggestions:
1. Choose 1 of your counters to generate your timebase to make it easy to experiment with timebases like 1 MHz that aren't directly available on the board. The other measurement counters should be configured to use it as their Timebase.Source signal (can be found in the DAQmx Timing property node.)
2. I assume you want the 5 measurements to start at the same time=0 point, right? You should configure all 5 to use the same signal as a digital "Arm Start" trigger. In LabVIEW, this can be found in the drop-down menu for the DAQmx Trigger property node.   I would typically use PFI0 as the trigger signal because this maps to the same pin that I can control via software as digital port0/line0. Thus, no screwdriver work for wiring a signal.
3. If you're buffering 5 measurements, you'll need to configure at least 2 of the tasks to operate in interrupt mode because the board only supports 3 DMA channels. This is yet another DAQmx property node setting.
4. There, now that the prelims are out of the way, here's how to get both pulse widths and pulse start times. It's gonna take a bit of work in software though.
   Configure the counters for semi-period measurement. This will cause the tasks to buffer up arrays with alternating values representing high times and low times of the incoming signals. You should be careful and always read even #'s of samples from the buffer, never odd #'s. You'll also need to configure so that you can predict which comes first -- high or low time.
The high times will be your pulse widths, and the cumulative historical sum of *all* the semi-periods up until that high time will be your timestamp.
5. Further description for handling 1 such task. Create a while loop for reading values from the task. Initialize a shift register to a count of 0 to hold your historical cumulative time.  (Note: depending on your duration and resolution, you may need to make this a double rather than an integer.)   Inside the loop, read an even # of samples from the task, say, 1000.   Pass the 1D array into the Reshape Array function to make it 500 rows x 2 columns.   Pass that 2D array into a For loop using auto-indexing. Also pass in the value from your outer loop's left-side shift register into an inner loop shift register. The inner loop will index out 1 row at a time. The pulse width will be either index 0 or index 1, depending on your config settings. Index it out and pass it out to the inner loop boundary with auto-indexing. If your pulse width is index 0, the left-side shift register represents the timestamp for the beginning of that pulse. Pass it out to the inner loop with auto-indexing as well. (If pulse width is index 1, you may first want to add the duration of index 0 to the cumulative time.) Finally, add the sum of indices 0 and 1 to the left-side shift register and pass it out to the right-side shift register. Pass this shift register out to the outer loop shift register. Pass the 2 arrays of data (pulse widths and timestamps) out to your main app via queue or something.
That's all the time I've got right now. I realize the info is packed kinda dense, but if you do some further searching on the terms I've brought up, you can hopefully figure out a good share of it. Once you've got it pretty close, post back and I can try to suggest some tweaks.
-Kevin P.

NI 6602 buffered pulse width and buffered period measurement with 2 counters synchronized during a defined time "

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