Digital triggering for analog acquisition on PCI-6024

I would like to initiate an analog input scan when a digital line goes low using a PCI-6024 board. I connected the digital line to TRIG, and the analog line to AIN0. I tried using "Acquire N - Multi-Digital Trig.vi"...it almost works. It acquires a scan, but it may (randomly) start at either the rising or falling edge of the trigger, regardless of the rising/falling trigger edge setting. How do I get it to only acquire data on a falling edge?

Dear Dave -- If you set up your task using MAX, you can specify whether you need to start acquiring at the rising or the falling edge. Using this task in your experiment should effectively take care of the issue.
You can do the same from LabVIEW as well using the DAQmx Trigger VI and set the acquisition to begin at the rising or falling edge as you may choose it to be.
HOpe this helps = VNIU

Similar Messages

Getting timestamp for analog acquisition with NI6110.

When I use the AI Read VI to get a waveform containing a sequence of scans, the waveform has a timestamp that presumably represents the absolute time of acquisition of the first scan as measured using the system clock. (I can't find any documentation on this, by the way. Where is this documented?) I notice that the AI Read VI can alternatively be used to return a "binary" array of measurements. For various reasons, I prefer to use this form of the AI Read VI, but I'd also like to get the timestamp that would be included in waveform returned by the waveform version. However, I don't want to call the AI Read VI twice, one time to get the binary array and a second time to get the whole waveform just so that I can g
et the timestamp. Is there a way to get this timestamp without getting the whole waveform?
Thanks,
Neal.

Thanks for replying.
I'm performing digitally triggered, buffered data acquisition with my 6110E, with the possibility of pretrigger sampling. The data I'm acquiring may extend several second before and after the trigger. Furthermore, my application may call the AI READ VI at some unpredictable time several seconds after data acquisition is complete. I'm assuming that the timestamp that would be returned as part of the waveform by the AI READ VI (whose exact nature appears to be undocumented) is calculated from the system clock at the time at which the digital trigger occurs, and wouldn't depend on when the AI READ VI was called. The article you referenced doesn't tell me how to do what I want. I want to get EXACTLY the timestamp that the AI READ
VI would include with waveform data, were it asked to return waveform data, but I want to use it to only return binary data. To the best of my understanding, the method described by the article for a obtaining a timestamp when binary data is retrieved provides no guarantee that the timestamp obtained will be the same one that would be returned as part of a waveform by the AI READ VI. Indeed, using the "Get Date/Time In Seconds" VI would seem, under the circumstances in which I would use it, to produce a timestamp that differs unpredictably from the time of the trigger by seconds.
Thanks,
Neal.

Digital trigger for analog scan

I need to synchronize the start of several measurements with a trigger. I am using a NI 4472 input card and PCI-6731 output card. I need to trigger an analog scan on the 4472, a voltage output from the 6731, and trigger a dmm to start scanning with a digital output from the 6731.

To trigger acquisition on the 4472 from a DIO line on a 6731, you would need to follow recommendations similar to Sal's. You could route the DIO line to a RTSI line on the PXI backplane, and then set up the 4472 to trigger acquisition off that RTSI line. You could also use an external connection and wire the DIO line to the "External Trigger" input on the 4472, and configure it to trigger off that signal. Probably the most important thing for you to do is make sure that everything that you want to trigger off that DIO line is setup and waiting for it before the trigger occurs.
You can also use the example finder to find examples that will work with each individual device. In the bottom left-hand corner of the LabVIEW example finder, there is a button that you
can click on to select or add the different pieces of hardware you want examples for. After you have configured that correctly, if you limit results to that hardware (check box), the only examples that you will see will be work with that piece of hardware. There are numerous examples of triggering on a digital line for the 4472. Hopefully this get's you moving. Good luck!
Logan S.

DAQPAD 6020e misses digital triggers during analog input (AI)

I am using a 6020E BNC DAQPAD to acquire two seperate 12kHz analog signals from a sonar through ACH0 and ACH1. The sonar generates a digital start trigger at the start of each ping to notify the DAQ that new data is to follow and i am using this to trigger my application through PFL0/ TRIG 1. Typical trigger repetition rate required/generated by the sonar is 20-30Hz but is selectable. My problem is that the board/software misses complete analog input data pings when the digital trigger repetition rate goes above 2-3HZ (ie I only receive 10% of the pings I desire). Analog sampling rate is 45kHz and I am acquiring 1-2kSamples per triggered acquisition. The problem happens using a Labview application based o
n a modified version of the shipped "Acquire N - Multi Digital Trig.vi" (and original). Any suggestions welcomed.

Hi,
I believe that the problem you are having is due to using the pause function to pause the acquisition before the next trigger and the fact that DAQpads do not have a DMA transfer mechanism. The default setting is to create an interrupt when the onboard FIFO buffer is half full. So when the pause trigger occurs there will always be data left on the FIFO, up to a half buffer of data.
To work round this problem you can use an external stop trigger instead of the pause.
Or it is possible to change the data transfer mechanism to cause an interrupt on every sample acquired instead of every half FIFO buffer. This will send every sample acquired by the DAQ board to the computer. The drawback is this method is very processor intensive and significantly slows
down data acquisition rates. As you are approaching the sampling limit of the card (100Ks/s or 50Ks/s for 2 channels) you may find that you will get buffer overflow.
To change the interrupt setting use the "Set DAQ Device Information.vi", which is located on the Functions Palette » Data Acquisition » Calibration and Configuration. See the LabVIEW help for information on using this VI.
Kind Regards
Tristan J
Applications Engineer
National Instruments

Designing digital filter for analog output

Hi all,
Iam working on pci-6723 NIDAQMX 7.3 LABVIEW 7.1 ENVIRONMENT.I have designed 16 channel data acquisition system.in order to supress glitches in the analog output signal ,which filter i have to adopt to the analog output generation. since i dont want to design hardware low pass filter , if i adopted digital filter will it improve the output signal performance ,kindly suggest me.with some example.
Regards
labview boy

Hello,
If you are talking about a software digital filter with the program that is producing the analog output, that will have no affect on an analog output signal. The glitching comes from the digital to analog converter (DAC). Check out this knowledge base article:
http://digital.ni.com/public.nsf/allkb/3BB2D5D837F6C9FE86256EAC007C123B
Really, your only solution is hardware.
If you are acquiring this signal on another data acquisition system and you want to remove the glitches from what you are seeing, you could use software filtering there.
-Alan A.

Can I use the 2 digital triggers on the PCI-6023E to trigger 2 seperate Analog inputs on the same board?

I want to monitor 2 analog DC signals (single point measurements, not a waveform) and I want to use the digital triggers to start the acquisition, 1 trigger for 1 AI. the measurements need to be made at 1Hz, maybe slower. Is this possible with the PCI-6023E?
If not what hardware should I be looking at? I have a total of 6 triggers and 6 AI.

Dimentia,
I would need confirmation on what you want to do:
1) I want to monitor 2 analog DC signals
This means that you will have one Analog Input operation monitoring two channels. Please confirm.
2) single point measurements, not a waveform
Ok, no buffers.
3) I want to use the digital triggers to start the acquisition, 1 trigger for 1 AI
This would mean that a single digital pulse or edge on a single line would start your 2-channel analog input operation. Please confirm.
4) the measurements need to be made at 1Hz, maybe slower.
Hardware-timed or software-timed? 1 Hz could be easily implemented with software timing. But the triggering could force you to use hardware timing. It will not be a problem but it would be good to know.
5) Is
this possible with the PCI-6023E?
Everything I mention above is possible with the PCI-6023E.
6) I have a total of 6 triggers and 6 AI.
This last phrase is what really confuses me and seems to contradict the previous sentences. Does this mean that you will want to perform 6 independent Analog Input operations, with its own triggers (one each)? Will every Analog Input operation have 2 channels?
I'll clarify why this is important:
- Each Analog Input operation can only have one hardware digital start trigger assigned to it.
- Only one Analog Input operation (multiple channels allowed) can be performed per board at any time.
Since the rates are so slow I would recommend that you perform sample all channels within a continuous acquisition and then discard the data that does not meet a certain condition. You could sample the triggers as well and discard those channels for which the trigger has not been received.
These are just some ideas based on my assumptions on the
problem. Assumptions are never a good thing so please confirm on the point s above and we'll try to help.
Thanks
Alejandro Asenjo
Applications Engineering
National Instruments

I am using an NI PCI 6024 E board device for an analog output application. Can I generate two independent waveforms, one on each analog output channel?

I am using an NI PCI 6024 E board device for an analog output application. Can I generate two independent waveforms, one on each analog output channel? In attach I send a example of my vi to control one chanel, but i need to control both but with diferent waveforms.
Is the vi correctly programed to this propose?

Yes you should be able to do that. look at the signal generation examples shipped with LabView
You can create a 2 D array, with each row representing a wave form per channel. The number of points of the wave form (per row of the 2 D array) represent the number of points in the output buffer
The wave forms can have different amplitudes/shapes, and therefore they are independent in this sense.
However, you need to set the update rate,which is the same for both channels. The update rate together with number of points per buffer determines the frequency of the wave forms. This means the two wave forms will have the same frequency.
To have different frequencies, you need to have say, on wave form with one cycle per buffer, and the other waveform have 2 cycles
per buffer. in a case like that the frequency of the second channels is twice that of the first channel, and so on
The two wave forms are then not truly independent, they may have different amplitudtes/shapes, but related in frequency.

Hardware digital trigger to start stop continuous analog acquisition

Hi I have seen the following example to use digital trigger to start and stop for finite number of samples. The example names is (DigitalStartandStopTrigger.vi)
in this example Reference Digital edge is used to stop acquisition but if I change to continuous then Reference Digital edge stops and show an errir. Could you please let me know how can I use hardware digital trigger to start stop continuous analog acquisition. An example would be really great
many thanks

HI tintin_99,
The way that example works (by modifying the read position of the buffer) essentially performs the same operation that the continuous samples mode does. That is to say, it is already a continuous acquisition.
The article below explains this in more detail, and the reasoning behind specifying buffer size manually and other tricks used. You may have already visited it in order to get the example VI, in which case it may be worth another read over.
http://digital.ni.com/public.nsf/allkb/BA775B0E445BFA79482571FE0032CCEB
Kind Regards,

I am using PCI-6033E IO card and i would like to send 5 volts (high logic ) to the trigger box. the trigger box will trigger the frame grabber card, that i am using for image acquisition.

i am using PCI-6033E IO card and i would like to send 5 volts (high logic ) to the trigger box. the trigger box will trigger the frame grabber card, that i am using for image acquisition.

Hello;
The first thing you need to figure out is the shape of the trigger pulse needed.
In case you just need a logic high TTL pulse, you can use one of the digital lines of your DAQ device.
In case you need a pulse train (multiple trigger pulses), you will need to configure one of the general purpose counters to accomplish that task.
You can find examples in both Labview and NI-DAQ showing how to program your DAQ board to accomplish both approaches.
Hope this helps.
Filipe A.
Applications Engineer
National Instruments

Digital audio adapter for analog phones

I would like to use the Toslink output and use a digital-to-analog headphone amp for my studio-quality headphones. I can find a digital to analog converter for quite a large sum of money - for me - at around $500.
1. Does anybody have any ideas for a digital to analog converter that won't break the bank?
2. Would I be better using USB as opposed to the Toslink/S=PDIF headphone output?
3. If USB is the better way to go, does anybody have any recommendations for a brand?
Thank you

Hi cube60
I'll let you have my old Pioneer Stereo Receiver for a $100, it supports Digital (Toslink) input and you can plug your headphones into it.
Not really, but be aware that you may already have or can find a real nice used receiver that supports digital input for way less than that amp. your looking at.
Dennis

Do I even need an analog to digital converter for old VHS?

I'm just trying the most cost effective way to transfer all of my old VHS & HI-8 material to a digital format for better preservation. Since, why I do not know, PE doesnt allow for analog capture, I need a converter like Dazzle to get my analog source to digital. Or do I?? Can I not just use Windows Movie Maker to capture then import into PE? Doesnt my capture card do convert?? I have my VCR hooked up via S-video to the card. Is the card not the same thing as an external converter? I just want to know the best way so I dont waste my time only to have to go back and redo everything. Thanx yall

Thanx y'all. Thats where I'm a bit confused. You mentioned "quality DV-AVI". I'm under the assumption that when I capture an analog signal that I set at 720x480 is a "quality DV-AVI". After I have captured and rendered to an .avi file I then import that into PE. Is that what you are meaning? Or is that an inferior quality video file? The capture card I have is a Legacy capture card that came with Pinnacle Studio ver 9. Pinnacle is a great intro level editor, but it sucks because it's slow, unstable and captures out of sync audio which I have to go in and manually sync. I shouldnt have to do that. I'll spend $100-$200 if thats what I have to do to get the results I want. I'm not looking for HD quality here. I simply want to capture all my old analog media, edit it, and burn to DVD and keep on my HD to preserve it all. I want it to be the same quality as it appears on its original medium.I also want to continue to edit and burn stuff using my Mini DV camera as well. I just want an editor thats above intro level, but not as complex as Premieire Pro. I feel that PE will do the job well. My capture card has S-video, firewire & composite inputs. Is my card not what I'm needing?? Or, do I need an analog to digital converter to get the analog material into a raw digital format thats the same quality as the original?
To help in my endeavors i recently upgraded and built anew PC so that I would have no problems, seeing that video editing does tax a computers resources. My new build is a Quad core 4 gb of RAM system. So my computer power should not be an issue for home editing and what not.

Triggering possibilities by the NI PCI-6052E board

Will you tell me, how to use the NI PCI-6052E board for analog and digital triggering. I want the trigger to begin the measurement, to acquire data before the trigger occurs. In other words, the board must response to a pulse input. Also I want to know other trigger capabilities of the board.
Thanks,
Gen

I am happy to let you know the PCI 6052E has both analog and digital triggering options. You can set your analog inputs to start acquisition on a rising or falling edge of your trigger pulse. If you are interested in acquiring data before your event trigger you can set up a buffer to capture pre-triggered data. Assuming you are programming with LV and Traditional DAQ you can reference the following app note:
http://zone.ni.com/devzone/conceptd.nsf/webmain/2A03115556FB233386256870005BB522?opendocument
If the link above does not work, go to
www.ni.com/support
under option 3. select 'Tutorial/Application Note'
Then do a search for 'Tips and Techniques for DAQ Triggering'
If you are using the LV 7 and the express VIs to set up your DAQ, look under the
triggering tab of the express vi to set up analog vs digital trigger and buffers for pre-acquisition. If you don't have LV 7, I highly recommend it because the express vi's will help reduce your development time.
-JVH

How to use digital trigger with analog I/O

How do I program analog input and/or analog output to start on a digital trigger (PFI pin) on PCI-4451/4551.
I have tried out various configuration and succeeded in starting analog input, simultanuous input and output triggered by the the anlaog input signal. I have also succeded i triggering 4551 from the dedicated EXTTRIG pin.
The problem is to trigger on a selectable PFI pin. I find the help for "AI Trigger Config" and "AO Trigger and Gat Config" misleading - some unsupported features seem to work while selecting PFI pin as source make the PC restart immediately.
I have not been able to find any LabVIEW example that shows how to use PFI pin as trigger input.
Using LabVIEW 7.1, NI-DAQ 7.3 on Windows 2000.
Kind regards / Med venlig hilsen
Torben

Hello
The PCI-4451 does not have any PFI lines. If you look at the user manual in the link beneath you will be able to confirm this by looking at the connector signal discriptions. The same is valid for the PCI-4451
http://digital.ni.com/manuals.nsf/websearch/6A32358C53BB15F086256660007392DC?OpenDocument&node=132090_US
The two ways of triggering that you have succeded are the analog triggering and digital triggering that you can peform with the PCI-4451.
Regards
Mohadjer

Noisy input on PCI-6024 card

I am having a problem with noise on my analog input on the NI PCI-6024 card. I applied a low pass and stll could not get the right voltage at the input. Am I missing anything? Do I need to ground all of the Ai grounds, ground the other inputs? Any advice is appreciated.

since you speak of AI ground, looks like you are using a Single ended mode(RSE)
I suggest you connect your Input in Differential Mode and see if the noise rejection is better.
But before that, can you tell what kind of signal are you feeding to the DAQ card??, is it a floating signal or a ground referenced signal??
then you can determine which of the following modes is best: RSE,NRSE or Differential
http://digital.ni.com/public.nsf/allkb/1FFCBE3451ABEE09862562970059881D
http://digital.ni.com/public.nsf/allkb/D509679FFAE2764386256297005D0C9D
This links should help you
First try this basic trouble shooting. if the noise is still evident, do get back and we could suggest other techniques to remove noise

PXI 5114 - Seperate Triggers for Each Channel

We are using a PXI-5114 High Speed Digitizer. We were wondering if it was possible to set different triggers for each of the two channels. We are analyzing a NTSC composite video signal and would like to observe two different lines of video in a LabVIEW VI.

I would like to clarify a little bit about what you are trying to accomplish. Do you have one or two separate video sources you wish to hook up to your digitizer? When you refer to "lines" are you referring to the individual horizontal lines that make up a single video frame?
The amount of time it takes to reconfigure the digitizer for a new acquisition is not deterministic and will depend upon the speed of your machine as well as any other activity you have going on over the PXI bus. As a result, reconfiguring in between an event may not be fast enough depending on how quickly you expect the image to be moving. I am also not quite sure how setting up a trigger for the top horizontal line and then another one for the bottom horizontal line will get the measurement you are looking for because each line will be refreshed at a periodic rate by the video source. Triggering on a specific line will give you a record with the digitized data for that line but it seems like you will need to do some kind of processing on that data to tell if the data contains this line of the digitized image contains is object you were looking for or not.
Please let me know if it does not sound like I am envisioning the application correctly.
-Matt

Digital triggering for analog acquisition on PCI-6024

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