Generate 1 microsec TTL pulse

hi,
i wanted a particular DIO pin say DIO1 to be in high state for i micro sec.how should i implement this?i am using Labview 6i on win98,PCI-6024

sithara,
I assume that you want to generate a pulse that lasts for only 1 micro second in the high state. This would not be possible with a digital line, but it is easy to do with a counter. You can have single pulse generation to specify the delay and the length of the pulse. As soon as you use the internal 20 MHz time base the counter should work just fine. The DIO lines on that board are not really meat for high speed switching, but the counter will do. I'm sure you can fine some premade code for this.
Regards,
Gazoo!

Similar Messages

How do i generate the TTL pulse from PCI 6024E DAQ card

Hi, I'm trying to write a program which generates a single TTL pulse when it is run. My goal is to generate the pulse, send it to the output channel of my PCI 6024E DAQ card, and then use a BNC cable, to display the signal on the oscilloscope. I have written the code and I think it appears fine but when I try to view the signal on the scope I am unable to see the pulse. I have tried slowing down the sweep on the scope and have adjusted the voltage and time scales but have not seen any response. After examing my DAQ card, I noticed that none of the PFI/TRIG terminals on the card are wired; the output channel connects to terminals for DAC0OUT and Ground. I'm wondering if this pin needs to be wired in orde
r to generate the pulse since PFI0/TRIG1 is the start trigger terminal. Any help would be appreciated. Thanks.
Attachments:
ttl.vi ‏26 KB

Hi,
You are looking for a retriggerable pulse generation. Please check the Generate Retriggerable Pulse (DAQ-STC).vi example that ships with LabVIEW.
Regards,
RamziH.

Need to generate a TTL pulse of 3 ms using USB Daq 6361

Hi all,
I need to generate a TTL pulse of 3 ~ 5 ms to trigger my external device. I am using USB daq 6361 with BNC connectors. I tried to use this examples(attached) but was not succesfull , can any one help me out in this, I just want a TTL pulse out to trigger my device. I tried to modify the example to see the wave form out but all it shows is a straight line. I want to generate a TTL pulse as soon as my program starts.
Am I using wrong example? should I use somethis else to generate the pulse. please let me know.
Thanks,
Attachments:
Capture.PNG ‏76 KB
Digital - Continuous Output_ttl.vi ‏65 KB

AnkitG wrote:
Jeff·Þ·Bohrer wrote:
Why would you create an Task with an analog output? its a Digital line you want to drive! and, just create it in the project.
Hi Jeff,
thanks but I couldnt understand , what you meant by create in project? Can you please explain. should I create digital line but I am still getting the same error.
Creating DAQmx items in Project Explorer saves the DAQmx object properties as part of the *.lvproj file. This can be very useful when the Task configuration does not change in the built application and you seldom want to use the task elsewhere. If you want to make minor tweaks to configuration of the run-time app there is even a human readable text file in the build output where properties like scale offsets, timing rates or ranges can be modified without redeploying a new app.
Jeff

How to generate a delayed retriggerable pulse using only one counter with PXI 6070E card

Hi
I have a problem in generating a retriggerable delayed pulse with a single counter(triggered through a signal at gate) using PXI 6070E card. VI was developed in NI LabVIEW traditional DAQ Ver.7.1. I have used the "delayed pulse generator config" VI and a "Start counter" & "Stop counter" VIs for the purpose. But there is no output seen at the out terminal of counter. So I introduced a "wait" VI and set it to 1 sec. Now the pulse output appears but some pulses are missing mometarily after every 1 sec interval. (any solution for this)
I have gone through a few similar requests in the forum but they suggest either to use two counters or to generate a finite pulse train which does'nt fit my application. Moreover PXI 6070E has only 2 counter timers. I am already using one counter to measure the frequency of a pulse train(signal 1). The application requires to generate a delayed retriggerable pulse for every pulse in signal 1. So I have only one counter left.
Can I measure the frequency of signal 1 by analog means.? so that I can use two counters for pulse generation. (Signal 1 is a TTL signal).
Request some help.
Thanks in Advance
Regards

A finite pulse train (N_Pulses >= 2) does require the use of 2 counters on most of our older hardware including your 6070E. If you're just talking about generating a single retriggerable pulse, you would only need one counter.
Here's an example in Traditional DAQ that shows you how to set a retriggerable pulse generation (it also allows you to adjust the characteristics of the pulse on-the-fly).
If you're writing a new program, you might consider switching to DAQmx as it supports NI's latest hardware and recent OSes should you ever need to upgrade. Traditional NI DAQ is no longer in active development. Here's an example of how to implement a retriggerable pulse generation in DAQmx. You should take note that you can't use the two drivers to simultaneously talk to the same piece of hardware, although you should be able to go back and forth by resetting the Traditional DAQ driver before switching to DAQmx.
Best Regards,
John Passiak

Counting TTL pulses at high speed

Hi all,
I am using PCI-6221 board with DAQmx to count the number of TTL pulses (which varies in its frequency between 0Hz to 10MHz) at a high speed (200,000 samples/sec.) and I am having a problem when the TTL pulse frequency drops below a certain level.
I am using CTR0 to generate continuous pulse train at 200kHz frequency to feed to CTR1 Gate input. I verified that the pulse train is being generated fine.
I am using CRT1 with buffered counting to collect the count for 200,000 samples at a time (duration of 1 sec.). I got the example code (Cnt-Buf-Cont-ExtClk) and pretty much used it as is.
CTR1 Gate is coming from CTR0 Out, which is 200kHz pulse train with 50% duty cycle, and CTR1 Source is the TTL signal that I am trying to count. At first, I thought that everything was working fine with the Source signal being at around 5MHz. Then, when I had the Source signal down below about 300kHz, I noticed that the program is taking longer than 1 sec. to collect the same 200k samples. Then, when I got the Source signal down to 0Hz, the program timed out.
I am guessing that somehow the counter is not reading for the next sample when there has been no change to the count, but I cannot figure out why and how.
Any information on this and a way to get around would be greatly appreciated.
Kwang

One thing you can try is to set the counter input CI.DupCounterPrevention property, this setting will filter the input, it is possible that when the ctr 0 is slow then many of the values you are counting become zero as well and are filtered out, since they are nolonger points, the counter will not collect enough points before the time-out occurs and the counter input read times out. I am not sure if this is your issue but I found out the hard way that this occurs when I switched to daqMX where this feature was added. Let me know if it worked,
Paul
Paul Falkenstein
Coleman Technologies Inc.
CLA, CPI, AIA-Vision
Labview 4.0- 2013, RT, Vision, FPGA

Can I send a TTL Pulse in a given rhythm?

I am new to LabView and using version 8.1.1.
I am trying to send a series of TTL pulses in a particular rhythm, (a train of 3 pulses at 50Hz repeated every 200ms). Is it possible to do this with accuracy?
Each pulse need to be accurate to the millisecond.
Thank you in advance.

Hello Lanny22,
Lynn is correct. If you have hardware timed (correlated) digital lines then you can do this by using the values he suggested. If you're using a National Instruments multifunction DAQ device with LabVIEW then I would recommend looking at this example program. Open LabVIEW and go to Help» Find Examples. Then navigate to Hardware Input and Output» DAQmx» Digital Generation» Cont Write Dig Port-Ext Clk.vi. This is the example program I would use to generate this pulse train.
Cheers,
Brooks

Tracking where I am in between TTL pulses

Greetings. I have a little Labview experience but very little with counters. I have a PCI-6602 card with a CB-68LP connector block. I have used up 7 of the 8 channels counting events so I have one channel left.
What I have is a Z pulse that is followed be four events and then another Z pulse. I know the point in the cycle at which each of these events occurs. I need to write in my program which event is occuring.
I apologize for the confusion. It's difficult to explain.
The ideal situation for me is that if the Z pulse is a 360 degree cycle I could track in my program if I am in the first, second, third, or fourth quarter of the cycle between Z pulses. I know that sounds almost impossible since my Z pulse can change.
For what it's worth, I CAN run one of the events in a separate TTL input if that helps me.
I have been trying to just reference the Z pulse to a timebase, then a little math would get it done for me but I don't have a full knowledge of counter/timers.
Any help would be appreciated. Sorry for the confusing post.
Dave B
www.signalg.com

I am measuring the speed of an event. To keep it simple, I am measuring the edge separation between TTL pulses. As the event moves through a cylinder it sets off probes that will send my system a 5 volt, TTL pulse. Knowing the time between the event passing probe 1 and probe 2 will tell me the speed of the wave. I have 7 probes in each of 4 tubes. Because we are running at 40 hz or less my boss would like to run all seven probes for each tube together. This way we are writing a smaller amount of data and only using a 7 channels of a counter card rather than 28.
So probe 1 in each tube will generate a pulse to the same channel.
To determine which tube I'm in I am referencing the spark for each tube. My plan is that when the spark for tube 1 occurs it initiates case #1. Spark 2 will make case 2 true, etc for 3 and 4. Each case performs the exact same reading on the exact same channels. Since not all tubes are exactly the same, each case will have custom formatting for that tube.
In each of these cases I am measuring the time between probes to figure speed. We can run one tube up to all four. My program should work for all without any intervention from the user since unused tubes will never send their corresponding case structures to true.
Using the 90 degrees per was when I was considering using the Z (timing) pulse to determine which tube is active. Now that I'm using sparks for each tube that is much simpler (I hope). The sparks coming into the DIO (adjusted to give me a clean TTL) will activate the case for their corresponding tube.
The 6221 is pretty affordable but I think this should work with what I have. If it doesn't I could sell them on another piece of hardware.
Do you think this will work?
Thanks
Dave
www.signalg.com

Triggering outgoing TTL pulse based on incoming position signal

Hello all,
For my research study looking at reflex responses in human subjects, I have the subject's ankle attached to a motor that moves the joint back and forth through a 30 degree range. I am sending a 5-V TTL pulse from a NI BNC-2090A to a constant current stimulator (Digitimer DS7A) each time the ankle passes a specific angle. I want one pulse sent out each time the ankle passes the target angle. The VI works fairly well, but it does not fire at the exact target I set 100% of the time (sometimes off by a degree or so). We are sampling at 2000 Hz, reading 100 scans per channel with the DAQmx Read.vi. The median of the position signal is constantly being evaluated and sent to the In Range and Coerce function, the output of which is sent to a Case Structure. The min and max inputs to the In Range function are set at what I have found to be the ideal parameters (translates to roughly + or - 0.5 degrees). If I set them any narrower, the pulse is not always sent out.
I've attached what I believe are the relevant parts of code. If anyone has any ideas of how I can make this vi run more smoothly and accurately, it would be much appreciated. Thanks in advance.
Attachments:
Trigger outgoing pulse based on position.vi ‏58 KB

Triggering with the DAQ card:
The 6229 unfortunately doesn't support analog triggering. Comparable cards which do are the 625x or 635x (also the more expensive 628x and 636x). On such cards there is an Analog Window Triggering feature that would produce the exact signal I think you are looking for (see X Series user manual). So if you have one of these handy or are looking to acquire new hardware then this would be a good solution.
Software detection for trigger signal:
If you want to continue using the 6229, see if something like the following would give what you want. Keeping the loop simple might help make this approach usable for your application depending on how long the window is you are looking for. It still isn't as reliable as a hardware-triggered approach.
External circuitry:
The simplest external comaprator circuit would just consist of an op-amp. You could use the analog output to set the threshold. The comparator output could trigger a counter output which would issue a pulse of some pre-defined width. The issue here is that the output signal would not be high during your exact window, but rather a fixed amount of time starting at the beginning of your window (so if the speed is changing it might not be what you are looking for).
You could in theory just build your own external circuit to generate the exact window trigger as well at which point you wouldn't need to output anything from the DAQ card (except for perhaps control voltages for this circuit). If you're at a university perhaps you could look for a EE student that you might be able to contract the work out to?
Best Regards,
John Passiak

How do I get the difference in time using 2 ttl pulses

Hi everyone, I have a question using the delay time. What I need to find the time interval between 2 incoming TTL pulses and fire the output TTL pulse precisely the same time interval after the second TTL pulse. I have been using Labview 7.1 with real time module and FPGA module (I think 1.0 because I can not find wait for rising edge vi). I am using NI 7830R card. The length of each TTL pulse is about 1-5 microsec. Second pulse comes in at about 1 millisec after the first one. So I need to fire aboyut 1 millisec after the second incoming TTL pulse. Because of the non constant TTL pulse length, I would like to reference at rising edge of incoming ttl pulses. Can anyone give me a help on this?
Thank you very much.
Hideya

Hi Hideya,
As is the case with many programming questions, there are several ways to go about solving this one. The solution I have in mind is to poll the digital input line for a transition from low to high. The simplest way to do this would be to use a loop with a shift register to store the previous digital input value. When the current digital input value is greater than the previous value, you can get the tick count (microsecond resolution sounds like it would be sufficient). You can then do that sequence of operations a second time. The difference between these two tick counts can be used as the input to the wait (microsecond) function. After that you can send your digital output pulse.
Best regards,
David H.
Systems Engineer
National Instruments

Counting TTL pulses within specified integration time

Dear all,
I have a PCI-6014 board, and I use Labview 7.1 and would like to do the following task with DAQmx7.4:
Analog source: analog square wave (or = 1Hz TTL pulses) produced by a function generator
Signal: photon signals from a photomultiplier (random TTL pulses)
I would like to count the photon signals at 100ms integration time, repetitively. But I don't want cumulative counts, just the number of photons (TTL pulses) in every 100ms. I would also like to make sure that I synchronize the counter with the analog source, i.e. to make sure I get exactly 10 data points in each analog cycle. ( I can't use the computer to start the function generator and it just keeps running., so I want to make sure I start counting on the starting edge of the analog wave.)
I used to do this with the traditional DAQ and connected the analog source to the "GATE" pin of the counter , so i could count "while gate is high" ( or while gate low, or count on rising edge/ falling edge. ) However I found some problems and I think my counter wasn't counting correctly, and I would like to rewrite the task with DAQmx anyway. Ideally I would like to separate the signals that occur in the first 1/2 and the second 1/2 of each analog cycle. But if that is not quite achievable, I can do the separation later when I process the data, provided that I know each 10 data points from the counter correspond to each analog cycle.
I have read several threads on the discussion board, but I still couldn't configure my applications using those examples.
Also I wonder if the "Arm Start Trigger" function is not available on my PCI-6014 card ? Because I can not find it in the Start Trigger property node.
Thank you very much for your reply. Any hint or advice would be greatly appreciated.
Joyce

...(Continued from prev post due to 500-char limit)
Now, here's a proposal for a method that should be able to work, though it'll require more data and more processing. One key area to watch out for under DAQmx is the property node for "Duplicate Count Prevention." The behavior changed between 7.1 and 7.3 (on E and/or M series, but not on TIO-based counters), then the defaults changed in 7.4, and something changed yet again in 7.5
Bottom line: you can set it to True or False. One setting will allow you to buffer up 0 values for intervals where there are no Source signals (photon events) within a sampling period (10 Hz hw clock). The other setting will not record anything in the buffer for those intervals. Clearly, you need the former setting, so you can always experiment to see how it behaves. I kinda gave up on trying to interpret it, understand it, or keep up with the differences by DAQmx version and DAQ board.
Ok, here goes: I'm going to propose that you actually oversample by about 10x and that you capture the Analog square wave in sync with your photon counts. Then your post-processing can determine for sure which samples correspond to Analog Square High and which to Low. You'll also be able to adjust for times when you get 1 too many or one too few samples in a square wave cycle, due to having independent un-sync'ed timebases.
So on one counter you generate a 100 Hz clock. The other one is programmed for buffered period measurement using the 100 Hz clock as a SampleClock and the photon pulses as the Source signal (this must be set up using a DAQmx Channel property node I believe). Remeber to be careful also about the DuplicateCountPrevention property.
You would further setup an AI task using the same 100 Hz clock as a Sample clock. Be sure that the 100 Hz clock task is started after starting both the other tasks. Also, be sure to always read the same # of samples from both tasks to keep the counter period and AI data in sync.
Voila! You now generate a data record of # of photon pulses for each 10 msec interval along with the voltage of the analog square wave at the end of that interval. A bit of post-processing and you're covered. If you're not required to manipulate data while the acq tasks are running, you can surely afford to bump up the oversampling rate considerably. The main advantage is to gain resolution on the time of transition of the analog square wave. For any interval ending with a TTL state change, you won't know where within that interval the transition occurred.
-Kevin P.

How can I control 3 stepper motors w/ amplifier by sending TTL pulses from DIO96

We have NI PCI-DIO-96 board and we have 3 stepper motors with amplifier and encoders. We want to control the motors by sending TTL pulses directly from the DIO-96 board to the amplifiers. Is this possible? What would you recommend if this is not a good approach? Thanks in advance.
Roman Zeylikovich

Roman,
Thank you for contacting National Instruments. While using a motion controller would be the recommended approach for any type of motion application, you may be able to use your DIO board to generate a TTL pulse train to control the step and direction inputs of your drive and motor. You will need to make sure that the current sinking and sourcing specification for the DIO-96 fits your stepper motor. That board is not designed to source very much current at all so this is one issue you will need to verify. Also, this board does not have any counter/timer logic that can handle quadrature encoder inputs.
Again, this digital device is probably not the best solution to control a stepper motor, but, depending on your hardware, could be configured to work proper
ly. The PCI-7334 is a low-cost stepper motion controller that can control up to 4 axes and is designed to easily accommodate these types of applications. You can browse through more information on our Motion controller boards at the following website:
http://sine.ni.com/apps/we/nioc.vp?cid=3809〈=US
Let us know if you have any more questions or comments.
Regards,
Michael
Applications Engineer
National Instruments

Count ttl pulse only over 2 V

Hi I have a problem while I was trying to count a ttl pulse by using the DAQ Assistant. The problem may be simple but I just cannot solve that since I am new to LabView.
There is a TTL pulse generated from our APD which is about 30 ns width, 5V. I want to use LabView to do the photon counting. However due to the noise, I would like to set a count limit of 2V, so the software only count the TTL pulse which is greater than 2V. But I cannot do that. There is no option to set the limit.
And our hardware is BNC-2110 and PCIe-6323.
Can someone help me with this? Thanks.
Solved!
Go to Solution.

Okay so perform a finite or continous read of your analog input. Then you can perform a threshold, where all values below 2 become 0. This can be done many ways but I'd suggest an auto indexing for loop and using a select function in the for loop. Then you can perform any normal edge detection you normally would to count pulses.
EDIT: Post some code if you can.
Unofficial Forum Rules and Guidelines - Hooovahh - LabVIEW Overlord
If 10 out of 10 experts in any field say something is bad, you should probably take their opinion seriously.

Can analog outputs simulate a 60hz ttl pulse?

The only outputs free on my 6020e are 2 analog. I need to drive a TTL device at 60hz. Can the analog outputs do this?

Paul;
You can do that but keep in mind that will not replace the counter pulse train generation operation. I'm saying that because the counter will execute a hardware operation, and so, will be able to have a completely system independent operation, generating a nice and accurate TTL pulse train.
By doing that trough the analog output, as the data transfer in between the computer memory and the DAQ board is system dependent (since it uses DMA), you might have some glitches at the pulse train because of some delay caused by the data transfer. But that is definitely something to try out.
Hope this helps.
Filipe

How to acquire analog signal and send a TTL pulse at the same time based on PXI 6123

Hi,
I am using a PXI-6123 data acquisition card, as the picture show in the attachment ,I want to acquire the analog signal of ai0 through reference analog window and at the same time send a TTL signal to trigger my camera. I have tried two methods, one is using the DAQmx Export signal.vi another is using DAQmx connect terminals, but when the data acquisition card acquire the analog signal, the DAQmx Export signal.vi and the DAQmx connect terminals sometime can send an TTL pulse ,sometime can not.
I don’t know why? or some other method that can achieve my arm is appreciated.
Regards
chunlei
Attachments:
method export signal.vi ‏21 KB
method connect terminal.vi ‏36 KB
Send a TTL pulse.JPG ‏288 KB

Hi,
Have things changed over the years?
I need to syncronise a digital output (Modul NI9474) and an analoge input (AI-Modul NI9203) module. I need to measure time intervals from a flank in signal A to a flank in signal B. I would like accuracies of the order of 1 ms. Currently, the signals are not synchronised, with errors of the order of 2 times the block length (block size x sample rate), sometimes much higher. The best I got so far was a block size of around 20 with a sample rate of 1 kHz.
If I use the master and slave settings on the RTSL settings, my program doesn't run properly.
If I use digital signals for input and output, I can syncronise them with RTSL settings and everything is good, but I can't always do that.
Also, if I do anything in the GUI (such as scrollowing something or going to another window), my output gets screwed up properly.
1. What can be done to synchronise AI with DO?
2. Is there something that can be done to avoid messing up the output when something happens in the user interface? (I know that I am messing up the outputs as they make some valves switch and that is loud).
Thanks in advance!

Generating frequency dependant square pulse and making it digital

trying to generate a square wave pulse at a specific frequency
it would be great if its simple as setting the amount of frequency (i.e., 50 , 50 pulses per sec)
but it gets complicated because of the sample rate
my problem is to convert it to digital and i don't know whats wrong
i attached a pic of my block diagram
as you can see, one pulse has frequency F, the other F/2, and lastly F/4
i need it to be compatible with the VI attached as well. can anyone help? thanks in advance!
Message Edited by sdkpark on 10-10-2009 12:19 AM
Attachments:
Create Digital Waveform.vi ‏20 KB
Correlated Dig Write With Counter.vi ‏31 KB

Hello again Sdkpark,
Apologies the message I was writing didn't include my full post. Take a look at this great community example for a prebuilt solution to what I believe you're trying to accomplish:
http://decibel.ni.com/content/docs/DOC-5763
Let me know if this isn't what you're looking for and I'll reply back. Have a great day!
-John Sullivan
Analog Engineer

Generate 1 microsec TTL pulse

Similar Messages

Maybe you are looking for