Generate two pulses train with difference phase

Hi'
Spec:
LW 7.1
Daqmx
NI PCI 6602
freq 300kHz
I want to generate two pulses train with two counters with a difference phase between them (change by user)
Thanks

Duplicated thread.
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Mathieu R.
  CTD - Certified TestStand Developer / Développeur TestStand Certifié
  CLAD - Certified LabVIEW Associate Developer

Similar Messages

Generating two pulse trains with on a PCI 6602 (2 CWPulse)

I am writing an application that should generate 2 pluse trains. I'am using ComponentWorks 3. I've tried to use 2 CWPulse but after configuring the 1st, i cannot start the other one because "too many controns are configured for this DAQ device".
Do you know how to use 2 CWPulse with a 6602 device ?

Dear Sir,
If you need to use two CWPulse components you will not be able to set a finite number of pulses to be generated. When you set the component to produce a finite number of pulses, it actually uses two counters to perform the operation. One is used to generate the pulses and the other one is used to count the pulses that are generated. You can use multiple CWPulse components as long as the pulse type is set to continuous on both components.

How can we generate a pulse train with variable inster pulse delays?

I want to generate a pulse train with random inter pulse delays (100us-10000us) and the pulse width would be 50-100us. I programmed for single pulse generation using counter cfg,a for loop contaning set attribute parameters pulse spec 1 and pulse spec 2. I changed the pulse spec 1 value in every cycle
This program is generating the pulses but not the exact values in the sense the some times the delays are more than 10 msec. As per the program the delay should be maximum 10 msec. please help me ASAP.
thanks
thota

Hey Thota,
I would suggest to take a look at the example program linked below. It shows how to change pulse specs on the fly. You have to be make sure you are ignoring a certain error when doing this.
Pulse Train Generation with Changing Pulse Specs (PWM)
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3E21756A4E034080020E74861&p_node=DZ52328&p_source=External
I hope this helps.
Regards,
Todd D.
NI Applications Engineer

How to generate a pulse train with different pulse width and delay?

How to generate a triggered pulse train with different pulse width. for example, after each trigger signal, let's say 2 ms, then the counter output a pulse with pulsewidth of 1 ms, and then after 3 ms delay after the first pulse, the second pulse was generated with a pulse width of 4 ms. Next cycle when the trigger signal comes, the same two pulses will be generated and so on. Is it possible to achieve this by using 6601 counter card? and if yes, how to achieve this? Thanks!

Unfortunately you can not create a hardware timed pulse train with different widths on each pulse from a counter. Whilst it can be changed on the fly using software, since you require a hardware triggered signal getting the software involved will not give a huge amount of accuracy when the pulse will actually change.
So in short you can't use your 6601 card (or a counter timer) to achieve this
There are three possible Alternative solutions
1 You could use a high speed digital IO device such as the (6533/34) to generate your variable signal which would require setting up the pulse train as a series of states based around the burst transmission mode where the clock would give you your specific timing.
2 A timed analogy output (for example on a MIO card with a clock (PCI-6220 / 62xx), i.e. Not the 6704 style static analogy output cards)
3 A high speed digital waveform card such as the (, 656x , 655x, 654x, 6534, 6533 (http://www.ni.com/modularinstruments/find_right.htm) ) this could then be scripted to work with your triggering and also there is a digital waveform editor which will enable you to set up the pattern you wish to generate (http://sine.ni.com/nips/cds/view/p/lang/en/nid/13555)
Hope that helps
Tim Matthews
NI (UK)

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！

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.

Trigged generation of two pulse trains

I have to write an application that will generate two equal pulse trains (with a given phase difference) on two different counters when I recieve a trigger signal. I'm using a 6063daq-card. If anyone have an related example, or some hint on how to solve this (elementary problem) please let me know.

Hi OG,
Although this functionality is present on NI-TIO counter/timer chips (NI-660x boards) by use of an initial delay within the counters (could program a delay equal to the desired phase shift) this is not available on DAQ-STC chips (E Series boards). This is because DAQ-STC counters do not support an initial delay in pulse train generation mode (driver doesn't support it).
The only way I see this happening is if you use the frequency generator on the E Series to generate your first pulse train (output on the freq_out pin) and use your two main counters to generate 1) a triggered and delayed pulse which will gate 2) your second counter which is a pulse train of the same frequency. To get the phase correct, your delay of the pulse should be equal to t
he desired phase shift of your pulse train period and should be gated/triggered by one of the rising edges of your frequency generator pulse train. The actual pulse width of this single pulse should be made as large as possible (or should toggle the output - see the 2nd knowledge base linked below). I have included a couple good references to get you started. Hope that helps. Have a good day.
How Can I Generate Two Pulse Trains without Using Both Counters on My E-series Data Acquisition Board?
http://digital.ni.com/public.nsf/ websearch/ 129541C85CEEDDBF86256ADF005C4409?OpenDoc ument
Using the General Purpose Counter (GPCTR) on the Data Acquisition (DAQ) Device as a Digital Line
http://digital.ni.com/public.nsf/ websearch/ B8A49A4E33F38AB686256B610061DC6D?OpenDoc ument
Ron
Applications Engineering
National Instruments

Generate a pulse train using a count from a quadrature encoder as the clock

I am trying to generate a pulse train with the same frequency as my quadrature encoder. Every time the encoder counts, I want the pulse to go high until the next count and then go low and so on. I am using a 6602 PCI card and a BNC 2121 accessory.

Maybe I'm not understanding your app, but I *think* you and I are approaching it from two very different directions.
As I understand it, you'd like to emit a pulse with each quad state change. Then that pulse would act as a counter Source signal. The counter will then increment on each pulse, to keep track of accumulated position. Further, you'd use your device-under-test (DUT) as a counter Gate signal, which would buffer the position count each time there's a rising edge on your DUT. The end result is a buffer of position values, captured at each rising edge of your DUT.
I'm talking about a different approach to produce the same data. You'd use 2 tasks on a M-series board. One of them is a hardware-timed digital input task based on "change detection." Each time one of the specified bits has a transition, your whole set of digital input bits can be captured and an internal "change detect pulse" is generated on the board. This task should be sensitive to the DUT edges.
The other task would be a buffered position measurement. It would receive the reference encoder inputs and internally do quad decode and keep a running count. The sampling clock for this task would be specified as the other task's "change detect pulse."
Net result: on each specified edge of your DUT, you'll buffer a reference encoder position value and a digital state of your DUT. You can choose to be sensitive to rising edges, falling edges, or (!!!!) both at once. You can also choose to be sensitive to many bits simultaneously. These are better capabilities than you get with the 6602 alone.
I *think* the 6220 should be ok, based on a quick overview of specs. I assume your 3.6 MHz is the rate of ref encoder quad state changes, right? In the approach I'm suggesting, you only need concern yourself with the rate of DUT edges which appear to be in the 10's of kHz or less.
Gotta go for now. Post back if any further questions.
-Kevin P.

Generating a pulse train

Hello everyone,
I'm using one counter timer from the DAQ card PCI-6014. I want to generate a pulse train with this output where I can control the number of pulses and the frequency of the pulse. The duty cycle is not important, I want to use the default value, i.e. 50%.
I have used the vi called "train_impulsion2.vi" with the following values:
-number of pulses = 10
-frequency = 1 Hz
-duty cycle = 0.5
When I connect the output from the counter timer 0 to an oscilloscope (pin 2 and pin 53), what I see is a constant 5 V for the 10 sec. I don't see the 10 changes from 5 V to 0 V as it would be expected. No falling or rising edges are observed.
However by using the DAQ assistant with the vi "daq_assistant_pulse_train.vi", with the following numbers:
-time high = 500 ms
-time low = 500 ms
-generation mode = N samples
-number of samples= 10
I'm able to observed what I want, i.e. 10 changes from 5 V to 0 V on the oscilloscope.
How can "train_impulsion2.vi" works like "daq_assistant_pulse_train.vi"? Thanks a lot
Marc
Attachments:
train_impulsion2.vi ‏21 KB
daq_assitant_pulse_train.vi ‏101 KB

Hello everyone,
Everything is now ok. I didn't put the correct leads inside the oscilloscope. That's why I wasn't measuring any rising or falling edges. Doh!!!!!!!!!!!!!
Marc

How to generate sequence of pulse trains with DAQmx?

I need to generate a sequence of pulse trains with DAQmx (the card I have is a PXI-6229 card). As an example:
- 10'000 pulses at 20kHz every 5 seconds with an initial offset of 2 seconds (let's say 10 pulse trains in total).
If I use the CreateVirtualChannel.vi in "CO pulse ticks" mode, I can only specificy offset, high ticks and low ticks, but not that the sequence of pulses should be repeated after some time.
Now I thought that I could solve this problem if it were possible to multiply two counter outputs: the first counter would generate the pulses (continuously) whereas the second one would switch between low and high on a slower timescale in order to gate the first counter, thereby providing an initial offset and the "off" phases between the pulse trains.
Is it somehow possible to multiply two outputs with DAQmx and the card I have? Or is there another solution to the problem?
Thanks a lot in advance for any hints!

Hi dlanger,
what you want to do requires a little bit more work.
First look at the example "Gen Dig Pulse Train-Continuous.vi" from the LV example finder.
This example generates a continuous* pulse train. As you see, you need a sample clock VI for setting the sample mode.
* NOTE: Generating a finite pulse train with a M-series card requires 2 counter.
With a pause trigger (DAQmx trigger property node) you can gate the output of that counter.
Now you have to generate a gate-signal with the the 2nd counter. That means, only if Ctr1-out is high Ctr0-out outputs the 20 kHz-signal.
Maybe you have to adjust the times in my example a bit.
Unfortunately there is just one "small" problem: "let's say 10 pulse trains in total"
This is not possible, because a 3rd counter would be necessary (*).
As a workaround you can modify the while-loop that both tasks are cleared after 50s. This is not brilliant, but should work fine for you.
A more sophisticated way is to perform a correlated DIO. So you can generate custom pattern for multiple outputs.
A good example can you find here:
Retrigger and Repeat Finite Digital Pulse Train in LabVIEW
http://decibel.ni.com/content/docs/DOC-8473
or here:
Generating More Than 2 Pulse Trains Using CompactDAQ
http://decibel.ni.com/content/docs/DOC-2167
Hope this helps.
With best wishes,
Ralf N.
Attachments:
Gen Gated Dig Pulse Train-Continuous.vi ‏38 KB

Generate a pulse train

How do I generate finite pulse train of 3 pulses of 25us pulse width, pulse period (1/(7000Hz)), and retrigger the same finite pulse train every 588.23us with the PCI-6602?
What are the externals connections?
What is the right Labview programming?

this can be done with the 6602 using multiple counters, but this board has 8 so you will still have many left over for other tasks.
You will need essentially 2 tasks, one taks is a retrigerable gated finite pulse train and the other is a simple finite pulse train.
I have done something similar using DaqMX and LV 7.0
To create the finite pulse train, create a CO.PulseTime task, create a channel setting the high times and low times (25 microseconds)and set the low polarity. I will assume that such a pulse train is going to trigger some external event or other DAQ card. Next set the timing to be implicit and sample mode to be finite and the number of pulses to be 3. To handle the retriggering and gate properities use a channel properitiy node and select:
StartTrigType = Digital Edge;
Start.Retrigerable = True;
Start.DigEdge.Edge = Rising;
Start.DigEdge.Src = PFI number of the out from the continious pulse train.
This last option will allow you to route the trigger from the controlling pulse trian to trigger your finite pulde train.
Now set up a second task to put out a continious pulse train with the period equal to the total durration between finite pulse trains (~500microseconds I dont have the exact number in front of me).
After creating these two tasks, start the retriggerable task first.
now when you start the continious pulse train you will get a finite pulse train of 3 pulses every time the rising edge of the continious pulse train fires. Stop and start the continious pulse train using software at will but only stop the finite task when you are done. Hope this helps.
-Paul
Paul Falkenstein
Coleman Technologies Inc.
CLA, CPI, AIA-Vision
Labview 4.0- 2013, RT, Vision, FPGA

Generating multiple Pulse Trains.

I am trying to generate two different pulse trains. Once the first pulse train has begun I need to start the
second pulse train approximately .69444 ms after the first has started. I am currently using the two counter channels on the NI ELVIS, but the second pulse doesn't always start after the first, but it does work sometimes. How can I fix this? Attached is my vi file.
Thanks,
David
Note: Each pulse train has a 33% duty cycle.
Attachments:
SaO2.vi ‏91 KB

Hello,
Here is what I would try:
1. Set up counter 0 to perform a continuous pulse train (see the LabVIEW example called Gen Dig Pulse Train-Continuous.vi)
2. Set up counter 1 to perform a continuous pulse train with a digital start (see the LabVIEW example Gen Dig Pulse Train-Continuous-Dig Start.vi)
A. Modify this example code so that the trigger source is your counter 0 output.
B. Modify this example code so that the initial delay value of the pulse train is 0.7 milliseconds (or whatever delay you want). Create the delay with the input to the DAQmx Create Channel VI (the delay is currently set with a default of 0.00 seconds).
What you are doing is triggering the second counter off of the rising edge of the first counter. So, counter 0 will start generating a pulse train. Counter 1 will not start until the rising edge of counter 0's first pulse has occurred. Once this trigger has occurred, Counter 1 will start (after the initial delay time of 0.7 ms has passed). You can cut and paste to put the code of the two examples together.
Hope this works for you,
Sam

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.

HOW TO GENERATE FINITE AND CONTINUOUS PULSE TRAIN WITH USB6216 AT THE SAME TIME?

Hello.
I am using a USB6216 DAQ and need to generate a 20 kHz signal using the
ct0 output and at the same time I need to generate a finite number of
pulses, say 9, on a software trigger using the second counter output
ct1.
Currently, I have two VIs that can do this separately, but when I want
to integrate these into one single VI y get an error in the finite
pulse train for ct1 that indicates that the requested task is already
reserved. I am thinking this has to do with the fact that maybe both
types of task use the same timebase but I have not found the way to
solve this problem.
Any help would be very much appreciated.
Thank you.
Sincerely
JSL

Hello.
If anybody is interested, the problem is solved.
There is no resource confilct if I generate the 20 kHz continuous pulse
signal using the frequency out terminal, and this way I can use both of
my counters as I please with no problems.
It's kind of fun to answer one's own questions...
Sincerely
JSL

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.

Generate two pulses train with difference phase

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