Frequency measurement with High Speed Digitizer using External Trigger

Hello:
I

Hello;
That is happening because you are doing Software timed operation, and since Windows manages all tasks that runs on the machine at any given time, your VI might take different times to execute, and that might be enough for you to miss some pulses.
The best way to do that is by using a 660x board, and have three counters doing the job. The firts counter can be configured as the first pulse train generator, the second counter can be used to generate a pulse that will trigger the third counter of. That pulse will be generated when the delay of 90 degrees is reached. So, the second counter will count events and will be triggered of by the pulse train generated by the first counter.
The third counter is configured as triggered pulse train generator, and t
he output pulse of the second counter is used as the trigger pulse for the third counter.
If you don't use that approach, you won't be able to reach fast speeds and might also miss some pulses, due to the Software timed approach.
Hope this helps.
Filipe A.
Applicaions Engineer
National Instruments

Similar Messages

Frequency measurement with High Speed Digitizer using External Trigger

Hello:
I have a

Hello Brooks:
Thank you for attention !
I will try to explain my application:
I need to measure a signal of a speed/position sensor. This sensor works with hall effect principle and is placed in front of a wheel with some teethes. Is used for automotive purpose in CAM and CRANKSHAFT applications. So, I need to measure period, duty cycle, rise time, fall time, Vpp, Angles for each teeth x encoder, everything from 40 to 7500 rpm.
I'm using CH0 to measure a signal of this speed/position sensor.
I'm using CH1 to measure a signal of an encoder connected to wheel.
I'm using EXT Trigger to sync acquisition with encoder's INDEX signal.
I need to measure the frequency of EXT trigger to know the instantly speed of the wheel.
So, If I know that my encoder has 2048 pulse/rev, I can measure FFT_FREQUENCY of CH1 with scalar measurement functions and calculate the speed !
The NI-Scope is wonderful because it can measure a lot of things automatic and fast, like period, frequency, duty cycle, rise/fall times ...
Now I have one more question:
I want to use 10:1 attenuation but I can't use a common probe. I want to connect the CH0 to sensor with a special connector.
I've tried to make the same circuit with 9MOhms and capacitor like explained on site, but I reached bad results. The industrial probes has special characteristics for capacitance and noise rejection.
Do you know how can I solve it ?
Thank you.

I have an NI5911 high speed digitizer and would like to acquire a video signal from a CCD using it. Does anyone know if this is possible without buying any more hardware please? If it is, how would I go about it?

The only thing I succeeded in finding on the NI site was about using a different high-speed digitizer in tandem with an IMAQ card but I was hoping not to have to buy an IMAQ card as it means I may as well not have got the NI5911 (a while ago) in the first place. Any help would be greatly appreciated!

You can certainly acquire video signals with the 5911. The only tricky part is that the 5911 does not have any video triggering options. That means that you will have to either find a way to provide your own trigger based on the video signal (that's where the IMAQ board comes into play) or you can just take a lot of data and keep only the data you need once it is in software. For instance, you could take one large record and then use software analysis to determine where the frame sync occurs. Hopefully this was helpful.

Urgent problem! please help. high speed digitizer, channel switch time too long!

Dear all NI high speed digitizer experts:
I post a question concerning the two-channel configuration using NI5154 digitizer (see Need help to configure a two-channel acquisition using NI5154 ).
As we need to do some measurement using NI5154 very soon so purchase a DAQ board as suggested by Efrain is not a option for our coming experiment. So I try to configure the NI5154 a two channel acquisition. I configure the NI5154 to count pulse in two channels. Our experimental setup will send pulse to channel 0 for 400 ms and then stop. 100 ms later pulses from other source will be send to channel 1 for 2 s. I thought the 100ms dead time in our setup would be long enough for the digitizer to switch from channel 0 to channel 1. But after some test I found the digitizer takes more time to switch between channels.
I made a test vi (NISCOPE-Timing.vi) just for count how many ms it takes for the digitizer to switch between channels. In the attached vi, if you run for only one channel one loop takes about 20 ms in my pc. If you run for two channels it takes about 130 ms for one loop. If you just run one channel twice the loop time is about 40 ms (I mean stop a channel and then restart the that channel).
I don't understand why it takes so long to switch from channel 0 to channel 1. As I tested the niScope Commit.vi consumes a lot of time for the second channel. Is there any way to avoid this? We can not extend the 100ms long dead time of out set up so I must get rid of this problem.
Solved!
Go to Solution.
Attachments:
NiSCOPE-Timing.vi ‏34 KB

Hi Lixin,
There are a couple of different options that you may try. The first, which it sounds like you may not prefer, is to use the TRIG line on the 5154 and somehow find a way to route both sets of pulses to that line. You can either somehow connect both lines to the one input or use some sort of external switch since the signals will not come in at the same time.
Unfortunately, what you re seeing in terms of the time it takes the board to reconfigure itself for a different trigger channel and re-inititiate is due to the settling time that is necessary for the board to be able to fully reach its specifications. The majority of settling usually occurs pretty quickly, but the board will wait for some time to get the best possible performance in terms of specs. If you are okay with reducing this settling time (and very slightly diminish the specified performance), then you can use an internal scope property to set the max settling time.
I have attached a .rc file which must be placed in the LabVIEW directory for niScope to enable use of this property node. Please place the file in your ...\Program Files\National Instruments\<LabVIEW 2009>\instr.lib\niScope directory. Once the file is in that directory, restart LabVIEW, and you should be able to see a new category in the niScope Property Node tree titled "Internal". Under that category, you will have the Max Settling Time property, which gives the driver a maximum amount of time (in seconds) to wait for settling before beginning a new acquisition. Add this new property to your first property node at the beginning of your program. I tested this out with a value of 50 ms and found that my initiate went from ~125 ms to ~53 ms or so after reconfiguring the trigger channel and re-initiating.
Hope this helps!
Daniel S.
National Instruments
Attachments:
niScopeMaxSettling.zip ‏1 KB

Synchronisation of M Series and High Speed Digitizer

Hello everybody,
i just have a question regarding synchronisation/timing of two different PCI cards (M-Series PCI 6220 and High Speed Digitizer PCI 5112, connected via RTSI cable).
I wonder how I can synchronise signals, because those cards use different mechanisms in Labview for timing and synchronisation.
Can anybody tell me, how I can synchronise the clocksignals and let them use the same trigger (actually I want to use the external trigger of the 5112)? Witch VIs do I have to use?
Thanks in advance
Oliver

Hello!
First of all many thanks for your reply.
Exporting the external trigger from the 5112 to 6220 via RTSI works.
Synchronising the clocks in the same way as you wrote doesn't seem to work. May be I did something wrong.
What I did was the following:
I exported the "reference clock" signal of the PCI 5112 using "niScope export signal.vi" to RTSI 7.
Than I used the daqmx "sample clock.vi" to configure the
clock. I used the instance "sample clock" with "dev1/RTSI 7" as
the source (dev 1 actually is PCI 6220) and as sample mode "continous
samples". I started the PCI 6220 (daqmx) first, after that I started
the 5112 (niScope).
Running this vi I get the following error:
"ADC conversion attempted before the prior conversion was complete.
Increase the period between ADC conversions. If you are using an
external clock, check your signal for the presence of noise or
glitches."
This is still a small problem, but meanwhile I came to a bigger one:
I thought I could use the 6220 in the same way I can use the 5112:
I want to fetch (or read) data on both cards contionously but also
periodically. The period time is given by the External trigger I
mentionend before. Till now I didn't find a way to aquire the data from
the 6220 in records of a given length (let's say 100 samples, at 1kHz)
every time the trigger occurs (External Trigger rate is about 250 Hz).
This is possible with the 5112 board, but I wonder if this is also
possible with the 6220?
Kind regards
Oliver
PS: Sorry for the "witch"

I have slow internet speed and having issue with download of photoshop cc is there an alternate I can go somewhere with high speed to download.

I have slow internet speed and having issue with download of photoshop cc is there an alternate I can go somewhere with high speed to download. without using this creative cloud that downloads first.

We need to know more about your system, please download EtreCheck and run the report and please post it on your next reply. Then we can see how your system is configured, what apps are on it and look for anything obvious. We will look forward to seeing your report.

Multichannel stream to disk high speed digitizer problem

Hi,
I'm trying to write a code for managing a PXI-5105 high speed digitizer as a multichannel data streamer to disk.
I found the code example on niscope folder (version 3.0) for a single channel datastreaming that works fine. I tried to modify this code,
according to directions included into the code for multichannel acquisition, but it fails. I wrote to NI support and they confirm that my code has to work.
For clarifying better my question, I include my code.
I'm a quite new labview user, I know that my code is not easy to read, but I hope that someone has already encountered my problem and may help me.
Best regards
Paolo
Attachments:
niScope EX Stream to Disk_Paolo_version.vi ‏86 KB

Hi Matthieu,
thanks for your attention to my problem.
The program runs, but it dispays only the first acquisition (first loop), and after there are no data acquired.
Using the single channel mode it works fine, you see a continuous acquisition on display and on disk.
I'm suspecting that there is a problem in the loop where I acquire fresh data (Using the lamp I haven't any data from the Niscope I-16 multichannel block, except for the first run where I get the first data).
I hope this clarify better the situation.
Best regards
Paolo

How to avoid losing data when communicate with high speed motor?

I connect with high speed servo motor via RS232. To avoid losing data. i thought to set receive buffer, only read the buffer if it collected all bytes. Is this possible?

Hi,
If you know the number of bytes you are trying to read, you can set a viRead call to return information once the particular number of bytes have been read. For more information on this, take a look at the KnowledgeBase article on a Serial VISA Read to read a requested number of bytes.
Even if you read before all bytes have been collected, you should not lose data. When the specified number of bytes are stored in the buffer, the viRead call will send the information to the program, and new data coming in will be stored in the buffer until the byte count is reached again.
I hope this helps,
Lauren L.
Applications Engineering
National Instruments

HT1498 I started downloading a rental movie on apple tv, but I live in a rural area with terrible Internet download speed...is there anyway to stop the download, and resume downloading, onto my iPad when I have access in an urban setting with high speed I

I started downloading a rental movie on apple tv, but I live in a rural area with terrible Internet download speed...is there anyway to stop the download, and resume downloading, onto my iPad when I have access in an urban setting with high speed Internet?

Yes, to be honest I was a little surprised myself. But it absolutely didn't connect when plugged into the test socket (I even tried to force a connection from the Home Hub manager but it wasn't having it). It is definitely the master socket. The only extension is a small piece of (engineer installed) phone cable to link the hub and the master socket (because the socket and mains power are unhelpfully on opposite walls of the hallway).
I ran the Java download for Google anyway and it only took about an hour. The speedtester results are as follows:
Download speed achieved during the test was - 109 Kbps
For your connection, the acceptable range of speeds is 50-250 Kbps.
Additional Information:
Your DSL Connection Rate :2560 Kbps(DOWN-STREAM), 448 Kbps(UP-STREAM)
IP Profile for your line is - 135 Kbps
I don't as a rule disconnect / reboot the hub; today it has been dropping off on its own, while several days ago I tried a few reboots just to try and get a connection.
Additional info - my exchange is actually called Claypole Fenton (or vice versa). Whatever, my profile has probably been welded to 135k for days and days.
Cheers
Nick

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

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

You should connect the signal (whose frequency needs to be measured) to Ctr-1, and there gonna be an internal connection between the output of the first counter and the gate of the second counter (as described here).
You may want to check this link as well.
I am not allergic to Kudos, in fact I love Kudos.
Make your LabVIEW experience more CONVENIENT.

How to measure the rotational speed by using rotary encoder and 1 counter?

I want to measure the rotational speed of a shaft, and I have below hardware:
1, a rotary encoder, with A,B,Z signals output;
2, PCI-E6363 card.
I do konw how to use such a encoder to measure the rotational angle by using the function "DAQmxCreateCIAngEncoderChan", but this time I need to measure the speed(rpm), as well as the dirction of the speed, which means a negative speed represent a CCW rotate direction.
More detail informations:
for the encoder, the A,B signal is 600ppr, and Z signal is 1ppr
the rotatinal speed is in range:　-300 ~ 5000 rpm.
some one suggested me that I can use the "DAQmxCreateCIAngEncoderChan" task to measure the angle firstly and then do the differential analysis with the angle. but I have to enable the Z index function, and it's hard to calculate when the shaft speed is fast then 2500rpm.
Anyone can help me on this issue?
Thanks in advance!

RobertoBozzolo:
Thansk for your reply. You are right that measure frequency to get the speed is the best way, but it's hard to get the dirction at the same time. You suggest me that "perform two angle measurements to get the sense of rotation", but I'm not sure I catched what you mean about this. I try to understand your opinion like this: distribute the signals to 2 counters, and start 2 tasks, one for frequency, the other for angle which used for deciding the dirction?
And by the way, in my application, the counter is limited:
I'm using PCI-E6363, which have 4 counters totally, and I have to measure 4 different speed sensors at the same time, so that means only 1 counter for me to measure the speed and the dirction.
RobertoBozzolo 已写：
To measure the speed from the encoder you can simply follow some of the frequency measurement examples that ship with DAQmx, considering that speed (rpm) is given by frequency (Hz) on one encoder output / 600 (ppr) * 60 (s->min) = frequency / 10.
Difficult is to add a sign to this measurement: frequency measurement gives you no information about sense of rotation, so I suppose you could perform two angle measurements to get the sense of rotation and then get the speed as above.

NI9411 frequency measurement with analogue output

I have an NI-9411 connected into a 9178 cDAQ module. I want to constantly measure the frequency of a digital signal then output this signal as an anlogue output using another of my NI modules. I am pretty new to the NI environment, does anyone know of a simple method using the DAQassistant?
Thanks for your help.
Richard

Hi Richard,
Do you want to output a voltage that varies with frequency or just an analog signal with the same frequency as the digital?
The easiest way for you to do this is to use two DAQ Assistant VIs and wire the output from your digital module into the output of your analog module.
If you wanted to output a varying voltage with frequency you would perform some simple scaling on your measured frequency and wire it straight to the output.
If you wanted a varying frequency analog signal, you could use the Simulate Signal express VI and wire the measured frequency into the frequency input.
The reason you only see four channels for frequency measurement is that this particular function utilises the hardware counters on your device to count the time period between pulses to work out the frequency, your cDAQ 9178 has four of these hardware counters.
For direct voltage level measuring you will see six differential channels available.
Hope this is helpful to you.
Regards,
Adam Brown
Applications Engineer
National Instruments UK

Using external trigger channels with PCI-1422

I need to trigger some 5 volt relays with my PCI1422 board similar to the way it is done with digital I/O on a standard board. Can this be done using the trigger channels? I have tried this and only get a 2V state change...

Hi,
How much current are your 5V relays pulling? Have you tried to measure the voltage change on your 1422 trigger lines with a Voltmeter without connecting it to the relays? The Trigger lines on the 1422 should give a 5V TTL signal, so something must be pulling that signal down.
Hope this helps.
Morten Jensen
National Instruments

How to simulate testing of PCI 5114 high speed digitizer

I want to use PCI 5114 board and want to interface it with LABVIEW 6.0 using NISCOPE VIs. I am a beginner to NISCOPE digitizer. I want to test my small application made for 5114. I don't have 5114 at present. Kindly tell me how can I simulate this boards and its input and Ext trigger.

Thanks Mr. Nathan.
My previous two posts were for me to understand how to check an application I had developed in LabView. As digitizer card is not with me at present so still some doubts are there. Let me specify in brief what I want and how I am achieving.
A repeated pulse signal of given duration (10 microseconds) at channel 0 is to be acquired. Repetition rate is decided by the trigger pulse available at Ext. Trigger. More clearly when ever trigger pulse (approx. Every 100 microsecond)) appears I have to acquire Channel 0 signal for 10 microseconds. Sampling rate is 100 Mega Samples per second.
I have used following blocks in given sequence: Initialize with Options (for simulation), Configure vertical, Configure Horizontal (sample rate=100MSPS, rec length=1000, num of records=1, ref positon=0), Configure trigger (edge, level=0.1, source Ch0 (for simulation purpose)), Initiate Acquisition, Multi Fetch WDT (num samples=1000).
Please tell whether I have to put Initiate Acquisition, Multi Fetch WDT Vis in while loop or only Multi Fetch WDT in while loop so that I can fetch all the data on each trigger.

High-speed digitizer

Bonjour,
comment je peux accéder au help de High-Speed Digitizers?
Résolu !
Accéder à la solution.

Problème de téléchargement? Utilisez de préférence le downloader pour les archive volumineuses (2Go de driver, yeeeha!). C'est la première proposition de la page de téléchargement.
Avant de se lancer dans un nouveau téléchargemetn de 2Go, vérifiez bien que votre version de LabVIEW est supportée - ce serait trop bête (NI-SCOPE 14.1 supporte LV 2011 SP1, 2012 SP1, 2013 et 2014), et qu'accessoirement, la carte que vous souhaitez utilisée est elle aussi dans la liste des matériels supportés. Pas de panique, dans le cas de NI-SCOPE, il n'y a que très peu de cartes non-supportés sous Windows Seven. Attention à la distinction 32/64-bits.
Le fichier readme reste la référence incontournable AVANT de lancer un téléchargement.
Cordialement,
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Mathieu R.
  CTD - Certified TestStand Developer / Développeur TestStand Certifié
  CLAD - Certified LabVIEW Associate Developer

Frequency measurement with High Speed Digitizer using External Trigger

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