Generate PULSE TRAIN VI & Measure Frequency VI

Can I RUN both Generate pulse train VI and Measure Frequency VI without either slowing down? Is Generate pulse train VI same as generate PWM VI? I have only attached the generate pulse train VI as I can only attached one file at a time.
Attachments:
Generate Pulse Train VI.vi ‏15 KB

Hi labview1958,
This depends on the kind of frequency you'd like to generate, and the range of frequency you'd like to measure. You didn't mention the kind of hardware and software (version) being used, so I'll assume you're using an E Series DAQ device and programming in LV 7.1. If you're generating a continuous pulse train, only one counter is required, hence there should be another counter available (for most DAQ devices). If you're generating a finite pulse train, two counters are required, and there'll be no counter available for frequency measurement. Also, frequency measurement can use one or two counters depending on the frequency range. You can find LV shipping examples (Help >> Find Examples) for both pulse train generation and frequency measurement. These make a good starting point for your development. In the case that you don't have a counter available for frequency measurement, you can also use the "Extract Single Tone Information" VI to measure the frequency in software.
These tutorials will provide more details:
Generating a Pulse Train with a Counter
Making Accurate Frequency Measurements
Hope this helps,
Lesley Y.

Similar Messages

PCI 6602:How can I use the digital lines of the board and in the same time to generate pulse train using a counter?

Hello!
My problem appeared when I tried to update my code from Traditional NI-DAQ Legacy to DAQmx.
I am using 2 counters (counter 5 and counter 7) from PCI-6602, to generate pulse train, and also the Digital I/O lines of the port 0 (the lines form 0 to 7). What I do in my application is that I am starting to generate the pulse train on the output of the 2 counters, and after that I am playing with the state of the digital lines.
In traditional there was no problem using the counters and the digital lines in the same time, everything was going perfectly, but in DAQmx this is not possible.
What happens: I start to generate pulse train on the output of the counters, no errors encountered, but when I try to modify the state of one line of the digital port the generation of the pulse train is stopped. This is happening when I start the task associated to the digital port.
My question is: it is possible to create a channel on the digital lines without altered the channels created for the counters?
Another thing what I manage to see using the "Measurement & Automation Explorer" and Test panels for PCI-6602, basically is the same thing, I generate pulse train on the output of the counter 7 and try to start a task on the digital line, but I get one error :
"Error -200022 occurred at Test Panel
Possible Reason(s):
Measurements: Resource requested by this task has already been reserved by a different task.
Device: Dev4
Terminal: PFI8"
Instead if I use the counter 0 or counter 1 to generate pulse train I don't encounter the same problem.
Which resources are used by the counters 2 to 7 from the PCI-6602 board and the counters 0 and 1 do not use?
Thank in advance for any replies!
Ciprian
Solved!
Go to Solution.

Hello Jordan, thank you for your reply.
I am sorry but I can not see or run your example, I don't use LabView, I use Visual C++ for developing.
Here is the code for generating the pulse train:
GeneratePulseTrain(unsigned long ulCount1, unsigned long ulCount2)
    short nStatus = 0;
    nStatus = DAQmxCreateTask("",&m_taskHandle);
    nStatus = DAQmxCreateCOPulseChanTicks (m_taskHandle, "Dev4/count5", "", NULL, DAQmx_Val_Low, 0.0, ulCount1,ulCount2);
    if( bTriggerMode == true) // if hardware trigger is enabled
       nStatus = DAQmxSetTrigAttribute (m_taskHandle, DAQmx_ArmStartTrig_Type, DAQmx_Val_DigEdge);
       nStatus = DAQmxSetTrigAttribute (m_taskHandle, DAQmx_DigEdge_ArmStartTrig_Edge, DAQmx_Val_Rising);
       nStatus = DAQmxSetTrigAttribute (m_taskHandle, DAQmx_DigEdge_ArmStartTrig_Src,"Dev4/PFI17" );
   //set the internal timebase
   nStatus = DAQmxSetCOCtrTimebaseSrc(m_taskHandle,"Dev4/count5","20MHzTimeBase" );
   nStatus = DAQmxStartTask(m_taskHandle);
    return nStatus;
And the code where I try to set the digital line:
SetChannelState(short nState)
    short nStatus = 0;
    uInt8 wrtBuf0[1]={0};
    nStatus = DAQmxCreateTask("",&m_taskHandle);
    // Configure line as output
    nStatus = DAQmxCreateDOChan (m_taskHandle, "Dev4/port0/line0", "", DAQmx_Val_ChanPerLine);
nStatus = DAQmxStartTask(m_taskHandle);
    wrtBuf0[0] = nState;
    nStatus =DAQmxWriteDigitalLines (m_taskHandle, 1, 0, 0, DAQmx_Val_GroupByScanNumber , wrtBuf0, NULL, NULL);
    nStatus = DAQmxWaitUntilTaskDone(m_taskHandle,10);
    nStatus = DAQmxStopTask(m_taskHandle);
    nStatus = DAQmxClearTask(m_taskHandle);
    m_taskHandle = 0;
    return nStatus;

Can I generate pulse trains on more than one counter output at the same time?

I have a PCI 6601 card with a BNC 2121 to connect the signals to two devices. The card is used as a trigger for both devices and I want to be able to generate pulse trains on two output channels at the same time, with a time delay between the two. How do I do that in Labview 7.1 Development with DAQmx?

I feel foolish for not being able to figure this out, but it still doesn't work. Attached is the VI I use now. Counter 0 generates a finite pulse train and I programmed Counter 1 to generate a retriggerable single pulse triggered by CtrOinternaloutput. I still get the same error message: -50103 The specified resource is reserved. The operation could not be completed as specified.
The same happens if I set the trigger for counter 1 at PFI36 (default output of counter 0) or any other PFI line. If I try a pulse train generation on only one of the counters, both work fine.
If I try the example in traditional DAQ for multiple counter outputs with phase delay, it works fine.
Can you tell me what I'm doing wrong?
Attachments:
Shutter_AND_lamp_trigger.vi ‏103 KB

How can I generate pulse trains whenever the value of the gate changes?

I need to generate pulse train both at the rising edge and falling of the gate signal. My DAQ board has only two counters.
Have a nice day,
Jun

Jun;
As your DAQ board has only two counters available, I'm assuming you are working with either one of the E-series board or SMIO boards.
If that is the case, your board doesn't have the capability of generating triggered pulse trains. And that is what you need.
You will need to use the 660x family instead. Those boards have the trigger pulse train capability. Regarding the second part of your application; none of the DAQ boards has the capability of triggering a pulse train generation at both rising and falling edges of the same trigger pulse. You can configure either as rising or falling edge of the trigger pulse. Then, to accomplish wath you need, you will need to configure two counters, both having the same trigger pulse triggering a pulse train gen
eration, and one configured to trigger the pulse train at the raising edge of the trigger pulse and the other to trigger at the falling edge of the trigger pulse; then have an external OR Gate which the two inputs are the outputs of those two counters.
Hope this helps.
Filipe

Generate Pulse Train.vi

I am updating a legacy application using LabView 5.1 and the DAQCard-500. I have NI-DAQ ver 6.9.3 installed. I installed NI-DAQ after LabView. I have no other versions of LabView installed on this machine.
I am using the generate pulse train.vi and get the following error message:
Error -10403 occurred at CTR Group Config.
Possible Reasons:
NI-DAQ LV: The specified device does not support the requested action (the driver recognizes the device, but
the acion is inappropriate for the device).
Looking a bit deeper I see that CTR Group Config is called in a subvi of Generate Pulse Train.vi but I do not understand why I would get the error message on the presumption that the Generate Pulse Train.vi is matched to the DAQCard-500.
Where might I be going wrong?
Is there a definitive way to know if I am using the correct .vi for the DAQCard-500?
How could I troubleshoot this further?
I have attached a .jpeg snapshot of the vi call just to show how I have wired the inputs.
Thanks in advance,
Bernie
Attachments:
Pulse Train Snap.jpg ‏10 KB

Ok the next thing to check is whether you can successfully access the board from the test panels inside MAX. If that works, I would try to find an example that sort of does what you are wanting to do and see if it works. If that works, start comparing the example code to the VIs that are in your example.
Mike...
Message Edited by mikeporter on 06-05-2007 08:32 PM
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How to continuously generate a pulse train with variable frequency

Dear all,
I am trying to use NI-USB 6259(BNC) to send Pulse signals to conduct position control of a servo motor with labview. The position control of servo motor follows these rules:
The number of the pulse train determines how many degrees the motor rotate ;( e.g. the angular position of motor)
The frequency of pulses determines how fast the motor rotate; (e.g. the speed of motor rotating)
The digital determines the direction of rotation of motor (e.g. clockwise or counterclockwise)
My question comes when I need to continuously generate a finite plus train signal in a period of time. Below is a sample:
Time(s)
Number of pulses
Direction of rotation
(1 is clockwise, 0 is counterclockwise)
Frequency
0-1
923
1
923hz
1-2
3540
0
3540hz
2-3
1751
1
1751hz
3-4
2663
0
2663hz
4-5
353
0
353hz
5-6
1017
1
1017hz
6-7
3436
1
3436hz
7-8
302
0
302hz
8-9
1513
1
1513hz
9-10
570
1
570hz
Here is the explanation of this table, the motor keeps rotating in clockwise direction during 0~1s. When the time reaches 1s, the motor just complete the rotation of 923 pulse signals. And then the motor starts to rotate in counterclockwise direction during 1s~2s. When the time reaches 2s, the motor just complete the rotation of 3540 pulse signals. So we can see that the rotating speed of motor in 0~1s is different from the speed in 1s~2s. Namely, the frequency of pulse signal in 0~1s is different from the frequency in 1s~2s.
I have already use the counter output of DAQmx, it just can generate pulse signal with certain numbers and certain frequency in one time. The attachment is the vi which can generate a finite digital pulse train from a counter output channel and the frequency, duty cycle, Initial delay, and Idle state are all configurable.
How can I continuously generate a series of pulse train with varying numbers and frequencies during a certain period of time.
Thank you very much for your help!
Solved!
Go to Solution.
Attachments:
Counter - Finite Output.vi ‏57 KB
Finite output.png ‏13 KB

Hi aacuna,
Thank you for your reply!
I already checked that article. The frequency in that Vi can change dynamically, but the method of adjusting the frequency is ‘manual’ .Below is the front panel of that Vi. When the Vi is running we can change the frequency by press the button.
Time(s)
Frequency
0-1
923hz
1-2
3540hz
2-3
1751hz
3-4
2663hz
4-5
353hz
5-6
1017hz
6-7
3436hz
7-8
302hz
8-9
1513hz
9-10
570hz
Thank you！

Finite pulse train with different frequency

Hello,
I'm trying to modify the labview example "generate finite pulse train" to generate a finite pluse train with different frequencies. Each freq will run 400 pulses. The freqs are stored in an array, which is being fed into a for loop. Thus ramp up the freq each iteration. However the program only generate 400 pluse at first given freq. I'm fairly new to daqmx and not sure what is wrong. Anyone have some idea how to fix it?
Attachments:
pulse train finite mod.vi ‏38 KB

The best "fix" will depend a bit on the needs of your app.
Is it ok to have a fraction of a second without any pulses each time you change frequencies? If so, then there's a pretty simple solution:
1. Outside the loop you'd create a DAQmx virtual channel and configure for Finite Sampling (# samples = 400) using DAQmx Timing.vi.
2. Inside the loop you'd chain together a DAQmx Channel property node where you set the pulse frequency property, then perform a DAQmx Start, a DAQmx "Wait for Task Complete", and a DAQmx Stop.
3. So for each freq in your array, you'll program the counter for that frequency, start the generation of pulsetrains, and then stop the task after 400 pulses have been generated.
If you must change frequency on-the-fly, producing *exactly* 400 pulses at each freq setpoint will be tricky, and maybe even impossible to do reliably.  Some techniques will get you closer than others though, so post back if you need to do this.
-Kevin P.

Generate pulse train

hello,
i have a question:
how to generate a 7 Hz pulse train with a daq dt304???
Thank you very much.

Found what I was looking for. The resulting page upon posting this question had a link to the LabVIEW palette upgrade for new counter VI's.

Generating pulse trains independent from my PC

Hallo,
I want to ask , how to generating a digital pulse with counter gate from my Labview 7.0 and that signal should be independent from my PC (My tutor said, even i shut down my PC , the signal will always be generated). I use Labview 7.0 , DAQ card , and Shielded I/O Connector Block SCB-68 . And which PIN should i use in that connector?
Thank you very much for any help.
Jimmy

Hello Jimmy,
Thank you for contacting National Instruments.
You can easily generate a pulse or a pulse train from your DAQ board using LabVIEW 7.0. If you choose to generate this output on counter 0, you will most likely need to connect to pin #2. If you choose to use counter 1, you will most likely need to connect to pin #40. You can connect to any of the DGND signals for a ground reference. These are pins: 35, 36, 4, 39, 9, ...
In order to actually program your board, I recommend that you use our DAQmx driver. I have attached two example programs below. One demonstrates how to generate a pulse and the other generates a pulse train. You can find these examples on your machine by going to Help >> Find Examples >> Hardware Input and
Output >> DAQmx >> Generating Digital pulses
You will not be able to have the signal be independent of your PC. First, the board must be programmed by your PC to start and stop the output. Secondly, your DAQ board is powered by your PC power supply. If you turn off the PC, you will effectively turn off your board.
Let me know if you need any additional assistance with this issue.
Regards,
Bill B
Applications Engineer
National Instruments
Attachments:
Gen_Dig_Pulse.vi ‏45 KB
Gen_Dig_Pulse_Train-Continuous.vi ‏57 KB

Signal generator Pulse train with switch cycle

Bonjour,
J'essaie de générer un signal avec un rapport cyclique tres variable sur une carte PCI6602
Par exemple,
j'utilise en signal source internal clock de 20MHz et je souhaite que mon signal soit de la forme suivante :
4cycles d'horloge à l'etat haut
puis 2cycles d'horloge à l'etat bas
puis 17cycles d'horloge à l'etat haut
puis 4cycles d'horloge à l'etat bas
puis 20cycles d'horloge à l'etat haut
puis 5cycles d'horloge à l'etat bas
pour cela j'utilise le generateur de signaux Pulse Train avec la fonction ND_SWITCH_CYCLE
mais en verifiant à l'oscillo je ne vois pas le signal varier de cette sorte juste appliquer le dernier rapport cyclique défini.

Unfortunately, I don't think you can accomplish that with a 6602. The only way to change the pulse specs on-the-fly is through software calls to the driver, and those won't execute nearly as quickly as you need. You would need to change the pulse specs for each and every pulse, and do it at a rate of ~1+ MHz. The software calls will limit you far below that -- I'd guess somewhere in the order of 10 kHz.
There's a further issue that you must let the prior pulse specs produce a pulse before the new pulse specs are allowed to take their place. So even for very slow pulse trains, it's difficult if not impossible to produce exactly one pulse at each set of specs.
What is needed (see my wishlist starting at reply #10-11) is the ability to perform hw-timed buffered counter pulsetrain outputs. Some of the M-series boards allow for hw-timed digital output at rates up to 10 MHz, but it appears that some of your intervals need to be odd multiples of a 20 MHz clock. Some of the high-speed digital boards could work, but you're looking at ~$2000.
How many cycles of precisely-timed pulses do you need? If 8 or fewer, there may be a way to setup a bunch of separate counters that are hw-triggered to start simultaneously, but each produces a single pulse with just the right specs. Then you'd need an output logic circuit which would essentially OR all the counter outputs together to produce the 1 output you need.
-Kevin P.

How can I generate synchronized pulse trains with 6602?

Hi,
I would like to generate multiple pulse trains with different frequencies with the 6602 TIO card. Currently I am able to generate pulse trains with different frequencies. But is there any way to synchronize all the pulse trains? For example, I'd like to have all pulse trains with their first low-to-high at the same moment.
Thanks!
Dan

Dan,
Absolutely, the NI-TIO chip on the PCI-6602 supports a start trigger. If you configure all of the counters that are generating a pulse train to use this start trigger, they will be synchronized. The example Generate Pulse Train - Start Trig (NI-TIO).vi demonstrates this process for one counter. In LabVIEW 7, this example can be found in the following location:
Examples >> Hardware Input and Output >> Traditional DAQ >> Counters >> NI-TIO
You will need to add code for the other counters, but this example should give you the general idea. Furthermore, this example demonstrates how you can use one of the digital lines to generate the start trigger.
Good luck with your application.
Spencer S.

How to drive pulse train out at lower frequency

Hi
I am using PCI-1426 to capture no. of frames using pulse train. Assume that I am capturing 25 frames per sec whenever pulse is high, which means that pulse train has a frequency of 25 Hz. I am also sending this pulse train out at external trig. But I want the same pulse train to be sent out at different frequency say at 5 Hz, which means I should get a pulse high after every 5 pulses of 25 Hz pulse train. Please tell me how can I do that?
Thanks
Sidd

Hi Sidd,
I still don't understand your hardware
First you wrote : "...and I dont need to send this pulse out at any external trigger."
From that I conclude that you trigger your camera by software. That there's no wire between the PC and your camera for the 25Hz trigger.
Now you write: "Suppose If I have generated two pulse trains of different frequencies as shown in IMAQ pulse train generation example."
So, what will it be?
Two hardware trigger lines or only one?
Regarding your question to Ben. The answer is in his post.
Maybe you overlooked the part : "...to ensure the these two pulses are synchronized is make sure you reference the same clock source..."
Can you make a drawing of your hardware, PC, camera, ..... and how they are connected.
That will clear out a lot of things
Regards

How can I use the pulse train from a 6602 to trigger an niFGEN and niSCOPE on each rising edge of the pulse train?

Hello,
Here is my application: I need to use a 6602 counter/timer to generate a pulse train of certain frequency and duty cycle. On each rising edge of this pulse train, I need to output an arbitrary waveform on Ch. 0 of an niFGEN (5422) AND acquire data from CH. 0 of an niSCOPE (5124). I also need to synchronize the niFGEN and the niSCOPE to the same clock used for the pulse train (6602/ctr0). This process needs to continue until the user stops the system.
I can generate the pulse train using the 6602 just fine using ctr0, but the pulse train shows up on OUT0 by default. When setting up the niFGEN and niSCOPE to trigger on rising/positive slope edge, OUT0 is not an option for either device as a source for the digital rising edge (pulse train). The main options for both are PFI0-3 and RTSI lines.
Questions:
1.) Is there a way that I can direct the pulse train to a location (such as an RTSI line) where BOTH the niFGEN and the niSCOPE can use it as a start trigger for each rising edge? I noticed in MAX that a route can be made between ctr0's internal output and a trigger line and others. If this is a solution, could you please explain how to accomplish this?
2.) Once I configure the niFGEN and niSCOPE to be triggered on a digital rising edge, how can I effectively have this happen for every rising edge from the pulse train? In other words, can I just initiate the FGEN outside of the while loop and it will generate a waveform for each rising edge it sees at the source until the while loop is exitted?
3.) Is setting a reference clock for the niFGEN and the niSCOPE the same thing as synchronizing both devices using the same clock that generated the pulse train? It is not clear to me the difference, and why it would necessarily be useful.
Images of my current front panel and block diagram are attached. If you would rather have the actual VI's just let me know. Any help and/or explanation on this is greatly appreciated. Thanks in advance.
Attachments:
Front_Panel_Control.jpg ‏278 KB
Block_Diagram_Control.jpg ‏263 KB

Hello Cgifford,
Welcome to National Instruments Forums.
To output your signal to the PFI lines,
you can use external connectios between OUT0 and PFI lines. You can also use
the backplane to do so by routing into the same RTSI line.
1)
On the SCOPE and FGEN, the name of the
terminals are actually “PXI Trigger Line x/RTSIx” but on the 6602 you might
need to route the signal using the property:
You can also use the DAQmx route signal which perform the same opperation.
2)
This will depend on the frequency of
your pulse train. If this is lower than about 10 ms, then you can probably
place this on a loop and start and stop the acquisition every time. If the
frequency is higher than this, you will have to use:
- Scripting on the FGEN side (read more)
- MultiRecord Fetch (more information in the scope help file
section “Acquisition Functions Reading versus Fetching”).
3)
The short answer is yes. The longer one
might depend on how tight you need the synchronization to be (us, ns, ps). For
very tight synchronization, you should look into here.
Message Edited by Yardov on 06-18-2007 03:14 PM
Gerardo O.
RF Systems Engineering
National Instruments
Attachments:
property.JPG ‏7 KB

Question of pulse train generation

Hi,
      I need to change the frequency of a continuous pulse train to control a stepper motor.
All examples I found is to update the parameters of a counter in a while loop. How fast
the frequency can be updated depends on the execution time of the loop. Most examples
have a 10ms delay function in the loop. I want to update the frequency in 0.01ms interval,
I wonder if is it possible to use this method. Is there a better way to do it?
      Thanks for help!
      Regards,
      Tao

Tao,
Unfortunately, you're not going to be able to update your frequency at a rate of 0.01 msec (100 kHz) for at least two reasons.
1. If you're using Windows, the OS won't loop at a consistent rate. The variations wil easily be in the order of milliseconds, possibly more.
2. The counter hw won't allow you to change a frequency until a full pulse has been generated at the prior frequency. You couldn't change the freq at 100 kHz unless the step rate was in the 100's of kHz.
I've been waiting for NI to provide NI-DAQ support for buffered pulse generation for about 7 years now, largely for the kind of stepper control you're describing. At this point, I've stopped holding my breath...
Meanwhile, there may be some other options. You could consider a dedicated motion control card. Or you could use a card supporting timed DIO (such as the new M-series cards). Finally, here's a link to an example I worked up that allows you to generate a finite pulse train with varying frequency. It isn't everything you need, but it might be a nudge in a useful direction...
http://forums.ni.com/ni/board/message?board.id=40&message.id=2411#M2411
-Kevin P.

Pulse Train Generation using PCI-MIO-16E-4

I need to generate pulse trains of changing pulse widths using PCI-MIO-16E-4 daq card using Igor Pro.
I have tried to use the CTR functions (but always keep getting errors and it doesn't work). I also used the general purpose counters (GPCTR functions) but cannot visualise them on a CRO. If someone can help in regards to the programming aspect, it will be greatly appreciated.
Thanks
Vakul

Hi Vakul,
Some questions that might help me to get you a solution.
Are you using Traditional DAQ, or DAQmx and which versions are you using?
What operating system are you running?
When you say you can't visualize them on CRO, I assume that you are hooking the counter out to a cathode ray oscilloscope and can't see the pulse train?
Are you going to need more than two different pulse widths for your pulse train?
There are several online knowledge bases describing how to change the frequency of a pulse train on the fly.
This link explains how to use software to create a new pulse width.
http://digital.ni.com/public.nsf/websearch/7B1B0427C39FE33086256CEE00752133?OpenDocument
This link discusses using frequency shift keying, which will only allow you to have 2 different pulse widths.
http://digital.ni.com/public.nsf/websearch/EC1F089252F33B248625696E006FB6FC?OpenDocument
I assume that you are writing this program to compile in Igor Pro using C. I can help you with the C code development, but don't know anything about the Igor Pro API.
Please get back to me about those questions and let me know if you need further help.
Michael Denton

Generate PULSE TRAIN VI & Measure Frequency VI

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