acquisition of several rates

Similar Questions

• Data acquisition period log rate Counter

  I measure and record the duration of a pulse train of digital entry (entry to the NI9421 card on a DAQ, series "C" chassis and recorded via LabVIEW SignalExpress 2009).  The acquisition stage 'Counter period' is configured to use ' 1 meter"measuring method.

  In order to save the data that I have to use ' 1 sample (on request)"acquisition mode.

  When I go through the saved data, how can I determine:

  (a) the sampling frequency of the recorded data points?

  point b) absolute timestamp of all the data?

  The log file has no information concerning the frequency of recording and my experiences, it seems to change based on the measured period of entry.

  Any ideas?

  Hi a.yearsley,

  Counters on cDAQ chassis 1st generation (9172) do not support measures clocked sample period.  I assume you are using this chassis since you mentioned that you have the module in slot 5 or 6.

  Your County of edge is very similar to the method of meter high frequency 2.  In both cases, you specify a length of time and count the edges of your external signal during this period.  The 2nd counter is used to generate the gate signal for the duration of time specified.  Your error with this method is up to 1 time of the external signal, it is more commonly used with higher frequency signals (I don't know what is the frequency of the signal).

  The standard method of 1 meter counts the number of ticks to a time base internally (80 MHz) for a period of the input signal.  As the signal itself, it is what is blocking the measure, the sample is locked in the buffer on the edge of the signal and is not clocked independently.  If you wish, you can configure the implicit synchronization, which gives you a period measured for each face of the input signal.

  Taking the stage above an idea more far, you could just set up a task to County of edge with the time of 80 MHz as the source database.  Use the external signal as a sample clock.  The only difference between this and using the standard period with implicit synchronization measure is that the counter is not reset after each sample.  This could make it easier to follow if you want to save a sample all the x seconds (that is, once the total passes a certain value).  You can find the period by subtracting the consecutive numbers and multiplying by the period of the time base (12.5 ns).  The meter would be turning after 53.69 seconds about, but if you read the County under the name of U32 there will be no problem with the subtraction (0000 - FFFF = 1 if the numbers are 32).

  If you're on cDAQ chassis 2nd generation (e.g. 9174, 9178, 9188), then you have not actually taken in charge for a period clocked sample measurement.  You can choose to enable a medium or not.  The user manual 9178/9174 has diagrams showing the extent of the clocked sampling frequency that is essentially the same thing (the driver reverse the measurement period for the frequency).  Must be guaranteed at least 1 m from your external signal between the sample clocks, if you use this method.  The clock can come from many sources - I would probably recommend using another counter to generate.

  Best regards

• Card FPGA and data acquisition synchronization

  Hi, we are control and data acquisition of several hardware devices (including Photodetectors and translational stages). Until last week, we used all the controls and acquisition using a PCIe-7852R FPGA board. However, we decided to move the acquisition part to a PCIe 6363 DAQ card to improve the sharpness of the tension. During the test, I found that the internal clocks in the FPGA and the DAQ cards are slightly inconsistent (not just a phase delay, but a difference in the period).

  I know because I have generated a square wave (period = 20) using the FPGA and gains using the data acquisition card (at a rate of 200 kHz, that is, 1 taste every 5). I have observed acquired place shifts 5 every 5 seconds approximately. Such a change does not occur if the production and acquisition is done using the same Board. Therefore, the only explanation is that the data acquisition and FPGA cards clock frequencies are different. According to my calculations, the percentage difference between their time clock must be 5/5 s = 0.0001%.

  Therefore, I wonder if there is anyway to synchronize clocks between them. Or, is it possible that I can drive the FPGA clock-based DAQ hardware, or vice versa? Also, please let me know if there is something trivial as I fix.

  Thank you very much.

  Kind regards

  Varun

  Hi Varun,

  my post was only one solution...

  Your data acquisition card may take an entry to control sampling of trigger. In this mode, samples draw on a rising edge of the external clock signal. As long as you stay within the limits of the DAQ (100 MHz for your card) material sampling works perfectly. There are even examples coming with LabVIEW explaining how to program your data acquisition card...

  This mode use you your FPGA as clock source sampling for data acquisition. Both will run on the FPGA clock in sync. When the FPGA is a bit out of 40 MHz, so it won't matter because both devices are triggered on the same clock signal...

• Several channels AND DAQ

  Hello!

  I have a problem regarding the acquisition of data from multiple channels. I get a channel data in time, but when I try to do a similar code to get data from another channel, it will not work. This can be done with the DAQ assistant, but I want to avoid this solution, because it slows down the program a little.

  The snapshot accessory show how this is done for 1 channel. Can I use a similar program for the acquisition of several channels?

  Thanks for your help.

  You must only specify several channels in your task - i.e. Dev1\ai0:1 and replace the DAQmx Read N channels. Go to the task in MAX and click the channels button Add. Follow the directions.

• Several cameras for machine vision

  We would like to use Vision Builder I do Visual inspection of our products. Due to the large size of the object, we might need several cameras

  to do this. Is it possible to use information from several cameras to Vision Builder or do I have to use several constructors of Vision at the same time? Are there

  other solutions?

  Kind regard

  Bert

  Certainly, Vision Builder AI can handle the acquisition of several cameras. If you trigger the cameras, the software can process even the images that have been acquired at the same time (although sequential processing steps, the step of acquiring image can be synchronized with other CQI steps if necessary for your application).

  The software includes templates to illustrate several different architectures of camera (see the new Template Inspection option under the new Inspection during the creation of a new inspection of the splash screen), and here are a few documents area dev that may also be useful:

  http://zone.NI.com/DevZone/CDA/tut/p/ID/6864

  http://zone.NI.com/DevZone/CDA/EPD/p/ID/6368

  Hope this helps,

  Brad

• Show the standard rate SSHRC

  Hello
  
  How to display flat rates that are attached to the benefit of SSHRC plans?
  
  After looking at the configuration of the standard rate
  
  Total compensation > standard rates >(Query rate) > treatment information tab
  There is a place for itself in order to accomplish the function display is grey and I can't change it.
  
  I'm having a problem because some fares are displayed and others are not. I am currenlty using 11i and the path of the nav is ESS > benefits > benefits of the view. How can I control what is posted and what is not?
  
  INTELLECTUAL PROPERTY

  Is your Plan Type-> display set to 'Vertical' or 'horizontal '.

  If vertically, then only you can display several prices - order is controlled by "Self Service display order.

  You can consult the metalink note: how to display several rate self-service benefits [1311833.1 ID]

• Signal conditioning equipment

  Hello

  I need to measure the frequency of several input (from 1 to 200 k) signals with 6024E PCI DAQ cards.  What signal conditoning hardware I need for this the simplest and cheapest way?  IE: convert the frequency of a voltage

  Thank you

  Curt

  A few notes:

  -6024E PCI data acquisition max sampling rate is 200 kech. / s, aggregate. This means that this clock frequency is shared between all channels. If you use a single channel of entry by card, you could reach 200 kech. / s/channel, but if you use two channels, this will be divided up to 100 kech. / s/channel. This is described in the E-Series user manual.

  -C' is relevant because even at a rate of 200 kech. / s, you can only reliable collect information on the frequency of signals slower than 100 kHz according to Nyquist. For the faster cards, see the M Series DAQ.

• Confusion between the MSO triggering behavior

  Hi people,

  I see some behavior confusing trigger on the ASM and I hope someone can help me understand what is happening.

  I have my FGEN you ed enter the two inputs of the oscilloscope and extinction of output. In the standalone VirtualBench, I put the FGEN for outupt a 1 Hz sine wave. Then I run the attached vi, which is just data collection. When I asked him to collect data on the same channel, as is the trigger, it fires once per second, which is what I expect. When I ask him to collect data from channel 1 and trigger off channel 2, or vice versa, it fires as fast I leave the while loop execute. This can be seen by the timestamp of trigger and also the chart update. This isn't what I expect, because I do not expect the choice of the data channel to influence the outbreak.

  Also note that I put the time pre-trigger at 2 ms, but it is 4 US when I question him. I don't know what changes this value. This may or may not be related, but happens to whatever the configuration of trigger/collection of data.

  thoughts?

  -Allison

  You don't set a time sample rate or acquisition. If you want to than to keep the settings that you made in the application of VirtualBench, you must set 'Reset' to 'false' on MSO initialize VI. Otherwise, they get to the default values. The default values for the acquisition and the rate of sample time are 250 MHz and 4 US, respectively. You set a time 2 ms pre-trigger, which goes far beyond the acquisition time, so he gets converted to 3,992 US (which is the largest value for pre-trigger, we can use with a US 4 acquisition at this sampling frequency time).

  In the intervention itself, in the API VirtualBench, you should activate the channel that you want to use as a trigger. If you configure an analog channel without mail in a trigger, your type of trigger gets under duress to a trigger immediate (you can see with the OSM query trigger Type VI). It was by design, even if I agree, in this particular case, it seems counterintuitive.

  The solution would be to allow two channels, but then only chart the channel you are interested in (you can use the table of primitive Index on the waveform to choose individual channels).

• How to acquire video lines

  Dear AE

  I'm working on the acquisition of several consecutive lines of video composite using Multi. Documents with my module PCI-5122.

  I did it with different ways to program the video trigger with configuration of different line numbers.

  I attached my LabVIEW, it's in LabVIEW 2009.  Can you help me check it?

  Thanks in advance,

  
  

• Multiple instances of VBAI

  I know that we can now acquire multiple cameras in VBAI (thanks!).  However, in my view, what to do so leads to very complex control sequences.  It doesn't look like VBAI has fully embraced parallelism for anything other than the FTP transfer.  What should I do if I have 5 cameras GigE each needs to be raised, and where it is possible that two can be triggered at the same time?  Can I run multiple instances of VBAI on a single PC (hey, it's multi-core)?  I predict that the current response is to use LabVIEW, but VBAI is especially LabVIEW... right?

  I want to retain only the simple, single camera, inspections on the PC.  Running multiple instances of VBAI would allow me to devote an instance for each camera without worrying about what's happening on TSF the other 4 (or more).

  No, I have not tried to do it again.  Currently, I am out of town and away from my vision laboratory.  I thought that if this is possible, it is worth mentioning to the public and if it is not, then, it is worth noting in R & D.  The system I'm imagining would be a future version of a system, we finished just where we had 4 NI Smart Cameras and a GigE camera.  The question is on what to do if all 5 GigE cameras.  Don't worry, we still love the SmartCams!

  On a sequence of validation.

  Dan press

  PrimeTest Automation

  Hey Dan,

  Good question! VBAI supports the acquisition of several cameras, even if they are triggered at the same time. We have a flag in the acquisition stage that allows to specify if you want to wait as the following picture or purchase immediately. Thus, in the case simple two cameras triggered at the same time, you will have an initial state who tried to acquire the camera 1 and if there was a timeout he loop back and try again using the wait for the flag of the next Image. When an image is acquired, you know that the other camera was triggered, so you transisition to another State who acquires the camera 2 with an immediate flag, since we know that the image is already there. You can use the image select to switch between the two images, so it is possible, but not necessarily the cleanest. Even if you had two VBAIs simultaneously, synchronizing is not trivial to make sure you weren't inspect imageN camera1 and imageN + 1 on camera2, but perhaps this would not be the cause of your system. In any case, we don't currently support multiple inspections VBAI operating simultaneously on a system, but it is certainly a feature that we know.

  Thanks for your series of validation,

  Brad

• LABVIEW 7.1 20020

  Hello I am the acquisition at a rate of 8000hz, 16 bit. My LowFc = 0.01 and my high FC is 1500 Hz. I always get this error 20020. I tried to play with the filter settings but that does not work.

  Why the filter gives this error?

  LabVIEW 7.1

  Thank you very much

  Self image. Now, the rest is up to you

• PCI, I / AO at a different frequency

  Hello

  As a newbie, I met a problem when I tried at the entrance and the analog output signal at a different frequency.

  I followed PID-control - Multichannel .vi to build a control program, so input/output can be synchronized. However, the project requires that the frequency of I be tenfold of the AO. I could re-write the while loop to make the output value constant for 9 of 10 cycles. However, in my view, it is simplest way to do.

  Anyone provide an example?

  Thank you in advance.

  Sincerely yours

  Ming

  lmuri wrote:

  Hello

  As a newbie, I met a problem when I tried at the entrance and the analog output signal at a different frequency.

  I followed PID-control - Multichannel .vi to build a control program, so input/output can be synchronized. However, the project requires that the frequency of I be tenfold of the AO. I could re-write the while loop to make the output value constant for 9 of 10 cycles. However, in my view, it is simplest way to do.

  Anyone provide an example?

  Thank you in advance.

  Sincerely yours

  Ming

  Hello Ming!

  Please use the Forums of NOR. You'll be happy to know DAQmx allows what I/O tasks such as these to be not run not only at the same time, but at different rates.

  The problem with the solution that you have imagined is that this implementation will remove the delegation of tasks to the hardware level, and your program would become software-driven; This becomes a problem when you perform tasks of acquiring data at very high speeds as it becomes limited to the speed of your operating system (OS).

  You can coordinate your tasks to operate synchronously and perform the output and the acquisition at different rates by creating a maintask. This means generally that you configure a task by DAQmx that keeps a clock frequency and you create tasks that use this clock frequency, or a division thereof, to exploit to their own individual frequency. This facilitated not only the execution of DAQmx tasks synchronous but also provide a material entirely focused on the solution of performance maximimse.

  Thanks to LabVIEW, if you go to help > examples find to open the Finder of example of OR. If you are browsing material input and output > DAQmx > synchronization > multifunction > Multi - multifunction - Synch Dig read write with Counter.vi, you will find an example of how to set up a counter as a master of the task to control the operation of operation both a reading and writing . (This example shows a digital but implementation may be easily replaced by analog).

  By setting the meter to the maximum frequency rate that you will require for your task (in this case, the speed at which you want to copy values) and apply it to the output of the SampleClocktask, you will drive the clock output task with the counter as the clock source. You can then use the meter as the source of the SampleClock for the task of entry, however to set the rate at any division of the driving frequency. In the case of your example, you can set the bit rate to 0.1 times the frequency counter to acquire a 10th of the rate.

  If you want to acquire at the same rate, but only to retrieve values on the 10th of the speed, this same solution can be configured to produce instead a trigger to return an acquisition in the buffer. With a master synchronizing the task, the possibilities are endless!

  I hope you find it useful, and if you need a precision more do not hesitate to let me know. Have fun with your DAQ!

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  Hello

  I wrote a VI to connect with a converter via the RS-232 serial interface. I'm sending point speed and reading speed and torque value continuously to the engine control. The only program works without any problem. But when I integrate the VI in the main program that measure the voltage and current through the acquisition of data (rate = 5 kHz), serial communication is disrupted somehow, I mean I get from time to time a few zeros for values of speed and torque that night my control loop.

  I have integrated my new VI just like any other loop in the main program and tried to play with the delay, but it did not work. It bothers me that this problem occurs randomly, as sometimes the readings are perfect for 5 min and sometimes from the first few seconds, I get a few zeros.

  No idea what could be the problem?

  Thank you very much

  
  

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  Hello friends. I noticed that adding a DAQ Assistant in a VI in a run to 60ms arise during the loop to 1200ms. I want to reduce this time to loop a few hundred milliseconds. This time cost is just a matter of the VI and DAQ itselves or my PC is also guilty?

  Is it possible to reduce this time by acquisition loop?

  Well, you have set the analogue acquisition at a rate of 1000 samples/s and ask for samples of 1000. Said simple arithmetic that will - 1 second. Said simple calculations that if you reduce the number of samples to 500, the acquisition will take 1/2 second.

• BlackBerry Smartphones must help BB8900 vs BB9700

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  trackpad-

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