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"

Similar Messages

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

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

Digital start trigger and high speed camera

Is there any particular option or way available in LabVIEW to initiate the data acquisition and high speed camera using a digital start trigger? If yes, shall I create a task for high speed camera and then synchronize it with the other tasks?
Kind Regards,

Hi Helen19411,
The way to trigger data acquisition in LabVIEW is to use the 'DAQmx Start Trigger VI'. To set this up I recommend taking a look at this example:
http://www.ni.com/example/25282/en/
Without any information about the high speed camera you are using, I can't give much advice. If the device is viewable in MAX then you may be able to create a task, and so long as you synchronise both channels in your code, the digital trigger should activate both events.
Kind Regards,
TomS
Applications Engineer
National Instruments

I have one application that has requirement to do low and high speed acquisition. I want to change sample rate while running. BUT... I have E series Device

I am writing control software for a process that is usually dull and
requires only 10 Hz acquisition rate. At particular times during
the sequence, however, we are interested in looking at a couple of
channels at 1000 Hz. My approach so far is to configure my
Buffered DAQ to run at the higher rate at all times. When we are
in the 'high-speed DAQ' mode, the program logs every point to
disk. In the 'low-speed' mode, I am picking off every nth (in
this case, 10th) point to log to disk. At all times, I update my
GUI indicators on the front panel at a maximum of 4 times per second (I
find that anything faster results in an uncomfortable display), so I
fill up a FIFO with data in my acquisition / logging loop, and read the
FIFO in the display loop. The data in my GUI display can be up to
250 milliseconds off, but I find this acceptable . As a side note, I
need buffered Daq with hardware timing, as software timing results in
lost data at 1000 Hz.
This all works fine and dandy, but I am convinced that it is not the
most elegant solution in the world. Has anyone developed a
buffered DAQ loop where the scan rate can be adjusted during
operation? I would like to change the rate of the E-Series card
rather than relying on down-sampling as I am now doing.
The reason I have concern is that at the moment I am simulating my AI
using MAX and when running the down-sampling routine, I consistently
miss a particular event on the simulated data becuase the event in
question on the simulated data always occurs at the same 'time', and I
always miss it. Granted, while it is unlikely that my measured
signal and my acquisition are perfectly synchronized in the real world,
this particular situation points out the weakness in my approach.
More than anything, I am looking for ideas from the community to see
how other people have solved similar problems, and to have you guys
either tear apart my approach or tell me it is 'ok'. What do you
think?
Wes Ramm, Cyth UK
CLD, CPLI

Adding to Alan's answer:
One of the problems that comes with these tricks for variable-rate acquisition is being able to match up sample data with the time that it was sampled.
If you weren't using either of E-series board's counters, there is a nifty solution to this! You'll be using 1 of the counters to generate the variable-rate sampling clock. You can then use the 2nd counter to perform a buffered period measurement on the output of the 1st counter. This gives you a hw-timed measurement of every sampling interval. You would need to keep track of a cumulative sum of these periods to generate a hw-accurate timestamp value for each sample.
Note: the very first buffered period measurement is the time from starting the 2nd counter until the first active edge from the 1st. For your app, you should ignore it.
-Kevin P.

Advice on buying camera for stills and high speed video

Hello video pros,
I'm a music composer who occasionally dallies with some simple photographic and video work. I'm looking for some advice re picking up a camera to make some simple videos, but with the highest quality I can get with consumer grade gear.
I am pretty much ruling out consumer grade camcorders for two reasons: One is that I want to be able to shoot high quality stills and make stop motion videos from very high res stills. The other is that I don't need audio recording at all because the video will always be just to accompany music - simple music videos basically. So I'm much more interested in the recent mid range point-and-shoot bridge cameras with full HD video modes rather than camcorders - they seem to cover more realistically the range of things I want to do.
My main question is regarding shooting at higher frame rates than 30 fps. I'd like to shoot video at a minimum of 60 fps (or higher) to then playback at 25 fps to get that smooth, slightly dreamy motion effect. There are a few cameras out there that offer high speed video modes, but most are nothing more than a gimmick because the res is so low that the resulting video is unusable. However a few cameras now seem to hit a sweet spot, offering 60 fps recording at HD res, and also 120 fps at 640x480 which (at a pinch) is usable, at least for stuff destined for simple web use.
The cameras I've narrowed it down to so far seem to be the Nikon Coolpix P500, the Panasonic Lumix DMC-FZ40 and possibly the Fujifilm HS20 EXR. I also was vaguely interested in the Casio Exilim HS cameras, but they seem to only offer high speed video modes that are pointless - 1000 fps at a completely useless low res, and 120 fps only at 640x480. The others I listed seem to offer at least 60 fps at some kind of HD res, so I'm assuming that with these cameras I could shoot decent looking video which would then play back with that slightly hyper real slow-mo effect when I import into FCP at 25 fps. Is this correct? Or is it the case that when they say HD video @ 60fps, it's some kind of interlaced mode which means you can't play back at a slower frame rate to get smooth slow motion?
The other thing I've noted is that all of these cameras do record HD video, but it's always compressed in H264 format. I understand that this puts a serious limitation on how much post-processing you can do to the video afterwards. Highly compressed video will begin to show image artefacts very quickly when you apply effects as opposed to higher quality (bigger file size) video compression. But I think I can live with that given that for the stuff I want to make, it will just be simply edited and only lightly graded. However, of the cameras I'm looking at, the Lumix also records in a format called AVCHD which (I think) does full HD at 17 Mbps. Does this mean that it's basic video quality is significantly better than the other choices? That said, from the specs it's unclear if it actually allows shooting at higher frame rates which you can slow down at playback.. the way it describes 60fps mode makes it sound like it's just interlacing so you don't actually get a higher number of images per second to then be able to play back at a lower frame rate. This for me might rule it out because I really want the creative effect of high speed video, even if it's only the subtle effect of 60 fps slowed down to 25.
So in summary, I'm looking for a camera capable of creative shooting (high quality stills to make stop motion videos, usable-quality HD video along with at least some degree of high speed video at a resolution that is still usable) to make interesting and artistic footage to accompany music. The destination medium is the web, so even though I'd like to get the best quality raw material to work with, the final destination is not exactly a cinema screen. As a pro in a related industry, I'm all too aware of the pointlessness of buying outlandishly over-specced gear that is far beyond your level of expertise. So I want to keep it simple and realistic, budget-wise, given the level I'm at. Nothing more than say $800 US. A seriously high end camera would be wasted on me, and I think it would be wiser to invest in useful accessories like a steadicam merlin and decent tripod rather than blow loads of cash on a camera far beyond my skill level.
Apologies for the long post, any and all advice would be very welcome and appreciated! And feel free to correct me if my assumptions are wrong, and suggest any gear that I should consider looking at.

Hi, thanks for your input. I'm aware of the fact that my question is a bit OT, but I'm just looking for input from people with more experience and broader information in this area than I have myself.. I know people are here to talk about FCP, but I'm betting many editors and film makers who work with FCP will have more insight in this area than I do.
I've been reading every review I can find at dpreview, and also am watching as many test video examples I can find on the internet, mostly on vimeo because the ones on youtube look pretty awful. I just am reaching out to get some actual experience and advice from people who might give me pointers on what to look out for.
As for 60fps not being fast enough, I know what you're saying. But for me, even 60 fps slowed down to 25 fps on playback is enough of an interesting effect, as long as the actual quality of the footage looks good to start off with. I like the subtle effect of slightly slower than real motion when it's real, bona-fide high frame rate slowed down. Artificially created slow-mo using plug ins looks cheesy to me, and the gimmicky super high frame rates of cameras like the casio exilim (where the resolution looks like a mobile phone video from ten years ago) are completely useless.
I've seen lots of examples on vimeo of stuff shot with DSLRs from Canon and Nikon at 60fps and then played back at 25 or 24, and it looks plenty nice enough for what I'm after. But am I kidding myself that I'd get anything near as nice with the price range I'm looking at?

Nikon D2x and High Speed Crop

Just an interesting observation....
With Aperture and Tiger, Nikon D2x images shot with the smaller MP High Speed Crop (HSC) mode displayed 24 extra columns/rows (depending on orientation) of pixels; thus an image that should be 3216x2136 showed up in Aperture as 3240x2136. The extra pixels included several rows/columns of garish purple and green pixels than needed to be cropped. This is fine for one image, but not suitable for several hundred (such as shot at a sporting event). In addition to the lack of support for .xmp import, this is one of the most frustrating things about Aperture (for me at least).
With Tiger this could be traced back (I'm guessing) to Core Image in the OS because other apps using it (such as Preview) displayed similar results. I was hoping for better results with Leopard and was disappointed to find the similar side effect. But I just checked and Preview, iPhoto, etc. no longer show these extra pixels in Leopard, only Aperture. My hope is that Apple will address this in an Aperture update in the near future (perhaps a RAW Fine Tuning 1.2 option).

I doubt that it's the camera, as the issue doesn't arise on exported pics. That said, as there are only two posts on the forums (yours and the one you refer to on the Aperture forum) it's possible that a: this only arises in very limited circumstances or b: it's local to your computer rather than a bug proper.
Create a new account (systempreferences -> accounts) and make a library there. Import a few pics and see if the problem is repeated there.
Regards
TD

New to Macs AND high speed internet. I'm a little unsure of what I'm doing.

I just bought my first iBook yesterday, and today my roommate subscribed to our local cable high speed internet. I'd like to configure a wireless network for both of us to use. Problem is, I have the Mac, and she has a desktop PC. Is there a way for the two to use the same wireless connection?
I'm sorry if this sounds like an elementary question, but I just want to make sure that I'm doing the right thing and that I get the right equipment. Thanks in advance for any help you all can give me.

Yes, you can use the same internet connection with a wireless router. Once the router is configured for your ISP (most have "Wizard setup" discs for PCs...from the Mac side you can use your browser to set it up) the iBook should find it and ask if you want to join the network. Just get a 802.11b/g compliant router.
John

Airport Express 802.11n and high speeds *impossible*

Hi there,
well I have been playing around for the last 24-48hrs with an AirportExpress 802.11n wiht the latest firmware on it, to achieve high speed wifi ~300mbps as 802.11n allows. The following hardware was used during this tests:
Airport Express Model: A1264 Firmware: 7.4.2
1) Macbook Pro AirPort Extreme (0x14E4, 0x88)|Broadcom BCM43xx 1.0 (5.10.91.26)
and an
2) 24" iMac - AirPort Extreme (0x14E4, 0x8E)|Broadcom BCM43xx 1.0 (5.10.91.26)
Goal: Achieve to establish a high speed wireless-n infrastructure network.
Comparing to: Ad Hoc Network Wireless-N iMac to Macbook Pro
Basic Ad Hoc Network Setup:
Macbook Pro:
PHY Mode: 802.11n
Channel: 11 (2.4Ghz)
Security: none
RSSI: -54
Transmit Rate: 130
MCS Index: 15
iMac 9.1:
Channel: 11 (2.4Ghz)
Security: none
RSSI: -48
Transmit Rate: 1117
MCS Index: 14
Testing: copy 1GB file via Finder Desktop to Desktop
Reault: achieved an avarage transfer-rate: 9.7MB/s
Infrastructure Tests:
1st Setup: identical setup with airport express
Configuration: Airport Express
Radio Mode: 802.11n only (2.4 Ghz)
Channel: 11
Security: none
Macbook Pro:
PHY Mode: 802.11n
Channel: 11 (2.4Ghz)
Security: none
RSSI: -36
Transmit Rate: 130
MCS Index: 15
iMac 9.1:
Channel: 11 (2.4Ghz)
Security: none
RSSI: -38
Transmit Rate: 130
MCS Index: 15
Testing: copy 1GB file via Finder Desktop to Desktop
Reault: achieved an avarage transfer-rate: 3.2MB/s
2nd Setup: airport express
Configuration: Airport Express
Radio Mode: 802.11n only (2.4 Ghz)
Channel: 11
Security: WPA2
Macbook Pro:
PHY Mode: 802.11n
Channel: 11 (2.4Ghz)
Security: WPA2 Personal
RSSI: -34
Transmit Rate: 130
MCS Index: 15
iMac 9.1:
Channel: 11 (2.4Ghz)
Security: WPA2 Personal
RSSI: -37
Transmit Rate: 145
MCS Index: 15
Testing: copy 1GB file via Finder Desktop to Desktop
Reault: achieved an avarage transfer-rate: 3.0MB/s
3rd Setup: airport express
Configuration: Airport Express
Radio Mode: 802.11n (802.11b/g compatible)
Channel: 11
Security: WPA2
Macbook Pro:
PHY Mode: 802.11n
Channel: 11 (2.4Ghz)
Security: WPA2 Personal
RSSI: -33
Transmit Rate: 130
MCS Index: 15
iMac 9.1:
Channel: 11 (2.4Ghz)
Security: WPA2 Personal
RSSI: -39
Transmit Rate: 145
MCS Index: 15
Testing: copy 1GB file via Finder Desktop to Desktop
Reault: achieved an avarage transfer-rate: 2.9MB/s
4th Setup: airport express
Configuration: Airport Express
Radio Mode: 802.11n (802.11a compatible)
Channel: Automatic
Security: WPA2
Macbook Pro:
PHY Mode: 802.11n
Channel: 36 (5Ghz)
Security: WPA2 Personal
RSSI: -48
Transmit Rate: 270
MCS Index: 15
iMac 9.1:
Channel: 36 (5Ghz)
Security: WPA2 Personal
RSSI: -46
Transmit Rate: 300
MCS Index: 15
Testing: copy 1GB file via Finder Desktop to Desktop
Reault: achieved an avarage transfer-rate: 5.5MB/s
Enabling/ disabling wide channels doesnt change the avarage transfer rate significantly.
These are just a few examples of all tests I have done, I have tried every possible configuration and took screen shots of almost 80% of the test (if someone is interested in reviewing this).
I couldnt find a single configuration in infrastructure mode that is as fast as the ad-hoc connection, so I assume either apple's setup for ad hoc and using channels is different to infrastructure or the airport express simply is unable to perform the same way as the wifi cards being used inside my Macs (which is my conclusion unless someone proves me wrong).
-------------------------------------------------------------------- Keep in mind, my findings show a 100% faster network in Ad hoc mode on a 2.4 Ghz connection
This is quite unsatisfying as I have bought the airport express on Feb 9th 2010 and it was the latest available model according to local genius bar.
So to quote apple: "The AirPort Express Base Station is based on an IEEE 802.11n draft specification and is compatible with IEEE 802.11a, IEEE 802.11b, and IEEE 802.11g." yes it might be compatible but doesnt allow you to fully operate at those specifications or has anyone been able to achieve this somehow?

why didnt I find this any earlier ...
http://www.applesource.com.au/mac-accessories/soa/Apple-AirPort-Express-Base-Sta tion-802-11n-/0,2000451112,339287629,00.htm

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,
.mrLeft{float:left} .mrInfo{border-left:solid 1px #989898;font-size:x-small;color:#989898}
Mathieu R.
  CTD - Certified TestStand Developer / Développeur TestStand Certifié
  CLAD - Certified LabVIEW Associate Developer

Verizon's new FiOS GigE Wireless N Router and High Speed Internet

So I got a deal in the mail to get an upgrade to [50/25] Mbps Internet (I currently have [15/5]...when I was reviewing it on line this message came up...
Verizon will provide up to [50/25] Mbps Internet with a wired connection. If you use your Internet primarily for wireless or WiFi connections, you have the option to upgrade to Verizon's new FiOS GigE Wireless N Router which will maximize your speed delivered through your wireless connection.
Upon completion of your order, you'll be provided with information for purchasing a router at Verizon's online equipment and accessories store.
I am VERY interested in getting super fast internet...my current internet is really good but it wouldnt hurt to bump it up. I have several devices using internet in the home...most of them wireless (including my PS3). I currently use a Verizon Actiontec router.
So here is my question...do I really need to get the above router to take advantage of that [50/25]? Also one other thing...My house is fairly large and I would really like to have two routers...is it possible to use two routers or a setup to have one upstairs and another downstairs?
Thanks in advance for the answers!
-Jest

There are a lot of variables that affect wireless range.
Walls, interference, other networks in the area, etc.
You don't indicate which older Actiontec you have.
Wireless capabilities also vary by Actiontec hardware revision (A,C,D,E,F,G,I).
In general, wireless range for 802.11n is somewhat less than 802.11g, even though the bandwidth is higher.
This is especially true on the 5Ghz band (which the latest Actiontec doesn;t support).
If you only need another 10 feet, you could try moving the router, or replacing the antenna with a high gain antenna.
http://www.meritline.com/high-gain-802n-2-4ghz-swivel-antenna-routers-network-card-adapters---p-4440...

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.

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.

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

Synchronisation of M Series and High Speed Digitizer

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