Measure a single pulse width using usb 5133

hi im trying to measure the width of a single pulseoutpout from NI SCOPE express
however pulse measurements.vi seems to expect more than a single pulse.
any ideas?
ta

Hi Slugger,
Can you first try this with the SCOPE Soft Front Panel (SFP) located in Start >> Programs >> National Instruments >> NI-SCOPE >> NI-SCOPE Soft Front Panel.
This should give you the screen below:
Please set the items as seen in the red boxes. Make sure your trigger channel is correct Mode is set to SGL and press the measure button.
This will give you a Scope measurement screen. Please press the Add button. Select the correct Channel and then in the measurement type choose "Period".
On the main SFP window press the run button. Does the measurement give you the reading you expect?
I do not have a Scope card to test this yet, so I have been using a simulated device.
Regards
JamesC
NIUK and Ireland
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Similar Messages

DAQmx Counter Input Measure a single pulse's pulse width

Trying to measure a single pulse's pulse width. It appears that the DAQ only makes the measurement on the read command instead of after starting the task. I just get a timeout error. Is there any way to arm to counter for measurement or am I better off making a seperate thread to trigger my single pulse?
double measured;
int numSamp;
TaskHandle taskHandle;
DAQmxCreateTask("", &taskHandle);
DAQmxCreateCIPulseWidthChan(taskHandle, "Dev1/ctr0", "", 0.025, 0.120, DAQmx_Val_Seconds, DAQmx_Val_Rising, "");
DAQmxSetChanAttribute(taskHandle, "", DAQmx_CI_PulseWidth_Term, "/Dev1/PFI10");
DAQmxStartTask(taskHandle);
//Trigger the single pulse here
DAQmxReadCounterF64(taskHandle, DAQmx_Val_Auto, 10.0, &measured, 1, &numSamp, NULL);
Thanks,
Dan

Which device are you using?
If you configure implicit timing (DAQmxCfgImplicitTiming) your measurements will be buffered and will begin when the task is started. The minimum buffer size is usually (always?) 2 samples, but that doesn't mean you have to read two samples back.
Best Regards,
John Passiak

Triggered single pulse width measurement

I am trying to measure the width of a single pulse, but would like to use the pulse itself as the trigger for a counter input pulse width read using a PXI-6608. I would like to do this since the pulse can come at any time (much longer than any practical timeout) and I would like to avoid having to place a DAQmx read in a while loop waiting for the pulse to appear. Also, while the pulse is high, I would like to produce front panel feedback (light a boolean indicator). I seem to be able to achieve that by using a digital input line, but again requires a DAQmx read in a while loop. I haven't had much experience with triggers and my attempts so far appear to seem like triggers are not compatible with counter input pulse width measurement. Is it possible to set up a trigger for a pulse width measurement?

Hello kayotik,
I think the best thing to do here is to use separate while loops. You can put most of your code in a main while loop, and then put your DAQmx read in a separate while loop. Both loops can run in parallel (just don't wire any outputs of one while loop to the other while loop, because then one will become dependant on the other). In order to pass data between the two loops, you will need to use a local variable. The DAQmx read can write to a local variable, and the main loop can read from that local variable.
You will also need to stop both loops with a single stop button. This article shows how (and also demonstrates the use of local variables to pass data between independent while loops):
http://digital.ni.com/public.nsf/allkb/267704CDE91156D186256F6D00711AAE
Colden

Single pulse width measurement

Hello,
I am trying to measure the time of a single pulse using ctr0 on a PXIe-6361.
The input signal seen in attachment Capture7.jpg, is going to PFI 9, the gate of ctr0.
The problem is that the counter see' s the rising edge and stops. The pulse width is not given as can be seen in the output (Capture8.jpg).
I get the same results using Meas_Pulse_Width.vi example.
Is something wrong with my PXIe-6361?
Solved!
Go to Solution.
Attachments:
Capture7.JPG ‏107 KB
Capture8.JPG ‏145 KB
Striker velocity blk_dia.JPG ‏35 KB

Hi,
I did pretty much the same and ran the example as well and they do work. You can try to explicitly specify the PFI line using a DAQmx Channel Property Node with a Counter Input Pulse Time Terminal property to verify if the problem is only with PFI 9 (if you use the property, you can use any PFI line even if is not the default gate for the specified counter), and even try with the other counters.
The VI is on the 2014 version, so I included a screenshot in case you have a previous one. If you need the VI in a specific version let me know and I'll downconvert it for you.
Camilo V.
Applications Engineer
National Instruments
www.ni.com/support
Attachments:
Counter - Read Pulse Time (On Demand).vi ‏39 KB
Screenshot.jpg ‏208 KB

Single Pulse Width with External Clock

I am trying to setup a 6602 counter for a single (non-buffered) pulse width measurement with an external clock. Under normal testing, the unit under test will provide the pulses, I need to measure the number of pulses during different time periods (1, 60, and 300 seconds). I want to do a pulse width measurement and I'll supply the gate signal pulse to the counter for the specific time needed.
Under normal operation, the unit under test is wired into the counter's source and the pulse is wired into the gate. For testing purposes I am using a BNC-2121. I have the counter's source wired to the Adjustable Square Wave Output and the gate wired to the Trigger output.
Here is my C++ code. I am getting a timeout error on the read and I don't know why. Any help would be appreciated.
   //Create Task
   DAQmxCreateTask( "task1", taskHandle );
   //Create Pulse Width Channel
   DAQmxCreateCIPulseWidthChan( taskHandle,             // TaskHandle
                                                   szCtrName.c_str(),     // Counter Name
                                                   "",                             // Channel Name
                                                  dMin,                          // Min Value
                                                  dMax,                         // Max Value
                                                  DAQmx_Val_Ticks,     // Units
                                                  DAQmx_Val_Rising,    // Gate Edge
                                                  "" );                            // Scale Name
   //Set the Pulse Width Terminal to the gate signal
   DAQmxSetCIPulseWidthTerm( taskHandle,     // TaskHandle
                                                 "",                       // Channel
                                                 "/CTR2/PFI38" ); // Terminal
   //Set the Timebase Src to the counter's source
   DAQmxSetCICtrTimebaseSrc( taskHandle,         // TaskHandle
                                                "",                       // Channel
                                                "/CTR2/PFI39" );   // Terminal
   //Start Task
   DAQmxStartTask( taskHandle );
//***Send pulse to gate counter***
   //Read Counter
   DAQmxReadCounterU32( taskHandle,                      // Task Handle
                                          DAQmx_Val_Auto,           // Num Samps to Read
                                          10,                          // Timeout
                                          ulBuffer,                           // Read Buffer
                                          1000,                               // Buffer Size
                                          &lSampsRead,                 // Num Samps Read
                                          NULL );                            // Reserved

I've setup a pulse width task in NI-MAX using the onboard clock and everything worked fine, so I know the hardware is working.
My unit under test is providing the pulses (from gyros) I need to measure. The pulses indicate the position of the unit so there are X, Y and Z axis gyros. I need to measure these pulses for specific periods of time (1, 60, and 300 seconds). For example during the 1 second measurement, the X and Y gyros should measure zero pulses and the Z axis should measure 515 gyros. During a 300 second measurement the X and Y gyros should measure < 60 and the Z axis should measure 30800.
So the gyro pulses are wired to the counter input and I am using a DIO channel from NI-6508 to provide the gate pulse. The gate signal will be high for either 1, 60, or 300 seconds depending on the test. The gyro pulses are essentially the external clock to the counter. I want to count the gyro pulses during the pulse of the gate (DIO).
To simplify the setup, I connected to BNC-2121 directly to the card. I have the adjustable clock output going to the counter input of ctr0 and the trigger signal going to the gate of ctr0. Once the task has been started and before the read ( I had a breakpoint set in the code), I would press the trigger button on the BNC-2121 and hold for approx. 1 second. I then execute the Read statement, and I always get a timeout. From my experience working with NI, I'm guessing I don't have a channel property set correctly, but its not obvious to me and I can't find an example to do exactly what I'm trying to do.
The CTR2 designation in the code was the object name of the card. I have two 6602 cards in my chassis. I was using ctr0 of the second counter card, so PFI38/39 was correct.
Again, any help would be appreciated.

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

Single pulse output on USB-6212 PFI

I am trying to generate a single pulse output on one of the PFI I/O lines on a USB-6212.
How do I go about creating the task? The pulse witdh is 100ms.
Also, how do I trigger from one I/O line to start another I/O pulse?

Hello johnswan,
The first thing you need to do is make sure that you have the NI-DAQmx driver installed. This should've came with your device, but if not you can download it from ni.com/updates. After the driver is installed it will add examples for LabWindows CVI. In LabWindows CVI you can go to Help » Find Examples to open the NI Example Finder and then navigate to Hardware Input and Output » DAQmx » Generating Digital Pulses. There is a DigPulse.prj which will show you how to create a digital pulse with a specific pulse width. There is also a project called DigPulseTrain-Cont-DigStart.prj that you can look at to see how to implement a digital start trigger. Take a look at these and let me know if you have any additional questions.
Regards,

Reading a PWM and determining pulse width using a digital input pin on a NI 9425 DAQ

Hello!
I have been experimenting with LabVIEW for about a week now and have run into a brick wall. I have found a fairly effective way of reading a PWM signal through an analog input and determining the pulse width. However, it is becoming necessary for this project to do this same thing using a digital input. I've been playing with this for about a day now and am not making much headway.
For reference, I will be using a 9524 device
Any ideas?

Also, if it is helpful at all, I've attached two vi's. One, functions just as I need it to - but it doesn't involve data aquisition. The second should be similar to the first, but is non functional - I keep getting an error that my amplitude is zero.
Any thoughts?
Attachments:
DigitalEdgeDetectionKnown.vi ‏47 KB
DigitalEdgeDetectionRead.vi ‏148 KB

External sample clock with pulse width measurement

Dear all,
I am using a NI 6220 board (programming with ANSI C) and would like to perform a "single pulse-width measurement" using an external gate signal and an external signal as source.
Using the "DAQmxCreateCIPulseWidthChan" command the program and card works only partly as intended. Namely, the external gate did work, but the card uses the internal 80 MHz time base signal instead of the external source connected to the default source pin (PFI 8).
I tried to route another PFI pin to the default source pin using the "DAQmxConnectTerms" command but this did not help either.
Obviously, I am missing something...
Best, Uli
Solved!
Go to Solution.

Hi Uli,
I posted to your thread here.
Best Regards,
John Passiak

When exactly do pulse width measurements start?

I am using a PCI-6601 to measure pulse width and period of a PWM signal in LabView (DAQmx).
I use ctr0 for the period and ctr1 for the pulse width. The period is measured between falling edges. As I am interested in the high pulses, the pulse width measurement is configured to start with a rising edge.
I do a buffered measurement with continuous samples.
I use a common start trigger (ArmStart) for both tasks.
Everything works just fine, but one thing puzzles me:
My start trigger can occur at any phase of the PWM signal, so I expected the first measurements to be invalid. This is true for the period measurement, but the pulse width is always correct. It doesn't matter in what phase my trigger occurs, the first reading of the pulse width is always correct.
Can someone tell me why?

This is speculation, but it's probably just that NI decided to follow slightly different rules for pulse width measurement than for some of the other counter measurements.
I've done triggered period and semi-period measurements before, but don't know that I've done triggered pulse width or frequency measurements.
For the two former cases, I know that the counter will start counting time immediately after the trigger edge. The first measurement represents the time from the trigger to the first active edge period (or semi-period) edge. It is often meaningless as you anticipated. For pulse widths, I suppose NI simply decided that the trigger will arm the counter but you also need the pulse's leading edge before you start counting to measure pulse width. So the first measurement is a true measure of pulse width and is never meaningless.
If this is true, then it may be tricky to sync / correlate the data in simultaneous measurements. For your particular app, you could get away with performing a single semi-period measurement and then calculating the periods and pulse widths. In other apps, it could get more difficult.
-Kevin P.

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

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

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

USB-5133, hws file to matlab

Hi all,
I use USB-5133 to measure voltages from two channels simultaneously. For that I use the NI-SCOPE. The scope saves the measured data as hws-file. I need these files in Matlab but I cannot open them. What would be the simplest way to export and open this data in Matlab?
All help is greatly appreciated!
Joonas
Solved!
Go to Solution.

Dear Colleagues,
Sorry for answering to this entry 2 years and a half later than the last comment, but my doubt is alligned with what you have been talking about. (Of course, if you consider that I should open a new line in the forum, just tell me, please.)
I have followed all your key points to read some *.HWS files i capture with a PXI NI5124 (12 bits, 2 channels).
I'm already able to read the data in labview and in Matlab, BUT I found a problem with the scaling of the data i have stored:
I took the signals simultaneously (2 channels) from -1V to +1V, but all the data have been stored in INTEGER number like:
16 112 32 128 96 64 80 80 0 32 -48 16 64 48 48 0 16 48 80 16 48 48 16 -16 16 -48 -80 -48 -96 -96 -80 16 -64 -16 -16 48 64 64 144 176 160 128 160 176 160 128 96 32 -16 -64 -160 -128 -160 -160 -176 -176 -192 -96 -32 0 48 48 112 80 192 192 192 192 208 160 64 144 32 -160 16 -64 -128 -256 -176 -128 -192 -208 -144 -48 -128 -256 112 320 16
These are only few samples, as I took 1.000.000 Samples @ 50 MSamples / s per file. I had some values up to +32000 and down to -29000, aprox.
I was surprised as i should had values like 0.001, 0.002 -0.2, -0.00005, etc.
The point is that I have found the scaling coefficients that are applied for each channel:
CH0 a:-1,143859 and b:3,2599724
CH1 a:-1,427364 and b:1,6671666
But I don't know how to scale the values i have registered down to the real ones. And I haven't found how this scaling works on the HWS files.
Thank you very in advance. I wold appreciate any help or int...
Best regards,

Output trigger pulse width

The data sheet on most (all?) the switch modules (I'm working with the 2530B, but that's really not relevant) mention that the output trigger pulse width is settable between 1uS and 62uS programmatically.
http://sine.ni.com/ds/app/doc/p/id/ds-330/lang/en
(about 1/2way down page).
However, I cannot find any reference to any property that you can set to modify this parameter. By default it's coming out at 2uS wide. I'm trying to capture the pulse using a microprocessor, but the pulse width is narrow enough that it's not getting it. There is no configuration for this in MAX.
I can't be the first person to try this. Anyone have any idea?

Hi Fast351,
You can program the pulse width using a DAQmx Export Signal Property Node in LabVIEW. From the property selection you would go to Events»Advance Complete Event»Pulse»Width Value. In C, you would use the DAQmxSetExportedAdvCmpltEventPulseWidth function.
-Jake B.

Measure a single pulse width using usb 5133

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