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.

Similar Messages

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

How to set & use digital trigger for AIN on a DAQmx?

1) How I configure a task to allow a digital input line to trigger a AIN reading in VB6.0 with a USB-6210?
2) To help me answer the above I created a task in Measurement & Automation Explorer that used a digital trigger (TRIGGER TYPE= DIGITAL EDGE, TRIGGER SOURCE = PFI0, EDGE=RISING). Then from VB I tried to figure out the parameters that were set. I had no luck. So, once I understand to achieve (1) above I want to be able to verify the resulting settings. What command(s) would I use?

Hi Hjehan,
I recommend checking the following knowledge Base that can point you to the different DAQmx examples.
Regards,
Faris A
Bueller

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

A quad B signal as trigger for analog daq trigger

Hi everyone,
I'm trying to use an A quad B signal to trigger my daq device to acquire current input.
The system information is: 32-bit Win XP, NI PCI-6236 counter card. The A quad B signal is generated by a hardware circuit simulator to work as the output of optical linear scale which is not installed yet.
All I want to do is collecting a current data at certain positions, like 20nm, 40nm, 60nm.... (for example, I use X1 coding, a period of A channel is 20 nm) so that I can plot out the current signal as a function of position. I specified the trigger as uprising.
I'm confused by the mechanism of "Sample Clock" and "Trigger" because they are both physically implemented by the A quad B signal. Am I right? So how to specify the sample mode and sample rate according to the trigger?
I attached the vi here and I can not get any chart plot out. I appreciate that if anyone could give me some hints on it.
Thanks,
Kang
Attachments:
use external A quad B singal as daq trigger.vi ‏57 KB

Hi Kang,
It seems that the circuit that you have generates a digital signal; I would suggest you to use this signal as your clock for the analog input.
You can find an example related to this if you open your NI Example Finder and go to: Hardware Input and Output » DAQmx » Analog Measurements » Voltage » Cont Acq&Graph Voltage-Ext Clk.vi
You’ll need to wire your digital signal to one of the PFI lines of your device.
Regards,
steve.bm
AE | NI

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.

Does the SCC-DI01 can be set as a trigger for strain gage measurement?

I used the SCC-SG01 to measure the strain. I need a trigger to activate the gages to get the data when the test happen. Can I use the SCC-DI01 as a trigger for gages for my test? If I can, how I can do it?

Hello hopezx,
The 2345 is a fairly passive device that does not actually have a lot built into it other than the signal conditioning. So the actual thing that we need to look at is the DAQ card that you have attached to the 2345. What you need to check on is the product page on ni.com to see if your device support digital triggering. If it does, then you can use a digital trigger for your task just like any other.
Please post back if you have any other questions or would like some more details. If you do post back, please make sure to let us know what other hardware you are using.
ColeR
Field Engineer

Analog start trigger for x series card gives an error?

Hi everyone,
I am having some trouble setting up an analog start trigger for DAQ using an x series PCIe card (6351)... Attached is my configuration... After reading the manual (http://digital.ni.com/manuals.nsf/websearch/08B4B2E1B5373B94862579BA006E6BAB), my understanding is that AFPI0 is a compatable analog trigger for the device; however, the vi will not run and I get an error... Although if I change the soruce to "Force" (which is ai0) it works..
Also, the device document says (pg 11-8):
"To improve trigger accuracy, do the following:
• Use an AI channel (with a small input range) instead of APFI <0,1> as your trigger source. The DAQ device does not amplify the APFI <0, 1> signals. When using an AI channel, the NI-PGIA amplifies the AI channel signal before driving the analog trigger circuitry. If you configure the AI channel to have a small input range,"
To me, this implies that I probably should use "Force" as the trigger soruce anyway (note that the instrunment is used to acquire data load cell data generated from human muscle contractions; so slew rates are relatively low compared to signals acquired from industrial tests).
Could someone please comment on these issues for me?
Regards,
Jack
LV2010
Attachments:
Untitled 1.vi ‏22 KB

Ok... I think I have answered by own question... APFI0 needs a low impedence signal to drive the terminal... I mistakenly thought this was an internal terminal or trigger...
So I should stick with using the first analog signal acquired in my DAQ device (e.g. ai0) as the trigger source?
Regards,
Jack
LV2010

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,

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.

Multi-buffered acquisition with digital trigger

I have a PCI-MIO-16E1 and I need to do three channel (250KHz/channel - ~400 scans/trigger) multi-buffered acquisition with digital trigger (trigger => 30 Hz).
I could not find any example of multi-buffered acquisition. Could anybody help me?

Hello,
I assume that you are refering to a retriggering setup where each time you recieve a trigger you take 400 samples on each channel at a rate of 250kHz per channel (total scan rate = 3CH * 250kHz = 750kHz).
In order to keep the system hardware timed you can use the two counters on the board to produce a retriggerable pulse train that will act as your scan clock. For example each time the counter recieves a trigger it will output a clock signal of 750kHZ with 400 or so pulses in order to take ~400 scans/trigger.
This clock signal can then act as the scan clock for your 3 channel analog input operation.
Now we have to figure out how to set up the retriggerable pulse train from the counters and have the analog input use the counter output as a sca
n clock.
Good thing there is an example that is already written
http://zone.ni.com/devzone/explprog.nsf/6c163603265406328625682a006ed37d/aab61e455564a04d862568930018e725?OpenDocument.
Good Luck.

No digital trigger signal on a PFI x-port in a PCI-6259

Hi,
I am using a PCI 6259 DAQcard (with a SHC68-68-EPM cable and version:2.9.1f0) to get an analog signal and a digital signal. The analog signal is used in NI MAX or NI Signal Express (DAQmn 9.7.5) to trigger it with the digital signal. When the digital signal is mounted on a Px/x port I can detect it. If I want to use it as a trigger signal on a PFI x- (better PFI x/Py.y-) .port I do not get any trigger quantitiy.
With a NI USB 6008 everything works quite well. Remark: The digital post is just labled as: PTI 0 and not as in the case of the PCI 6259 on the NI CB-68LPR-board: PFI x/Py.y.
Another remark is that I did not measure a voltage difference of 5 volt at the provided port.
How can I fix the problem and use a PFI x/Py.y-port for a digital trigger?
Solved!
Go to Solution.

Hey AndGar,
by trying I found one chanel on the platine with give me an trigger signal. So I can measure something but not in every chanal.
Maybe just the PFI x- ports are reserved for triggering and you need to close every other task which measures a digital signal.
*actuall I have no access to the programm*
Thanks and best regards,
Marcus

Using LabVIEW to program a Pattern Trigger for the PCI-5112

I am trying to program a pattern trigger for the PCI-5112. Has anyone ever done this? I am trying to use the the "Fetch forever" example as a base, then use the software trigger when there is a pattern match.
Any help or advice with this would be very appreciated.
PS as an example, I want to trigger when the pre-trigger data matches the pattern, say a 8 bit word such as 1010 0000. Maybe I can try to do like my Tektonix TS5104B scope and try to program a timeout trigger.

Good morning Andronicus,
Thanks for contacting National Instruments with your issue, we'll try our best to resolve it for you as quickly and efficiently as possible.
Unfortunately, there is no easy way to do what you're trying to accomplish with simply a Scope alone. The trigger input and PFI lines have no buffer and are only capable of looking for a single edge, and the standard CH0 and CH1 inputs strictly represent signals in analog.
So your current approach may be best, of using the Fetch Forever to acquire the signal into a prebuffer and then analyzing it and sending a software trigger. So the best you can do in terms of response will be software-time, which is not ideal. There is also the very tricky matter of interpreting that analog signal as a digital signal. You'd have to know the clock rate of the incoming pattern and then also the phase in order to correctly assess the incoming pattern. No easy task, and certainly nothing that would be super reliable or recommended.
Your best bet would be to purchase one of our HSDIO cards, such as the PCI-653x that inherently does pattern triggering in the hardware domain, and then route the start trigger (i.e. when the pattern has been matched) via a RTSI cable to the Scope card which can then simply use the digital edge trigger to begin it's acquisition. This will be far more robust, easier to code and have a much quicker response time.
Best of luck with your project.
Sincerely,
Minh Tran
Applications Engineering
National Instruments

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

Digital trigger for analog scan

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