thyristor pulses LabView 7

[John Wesly]

I'm doing a project in Lab View 7 in which I need to produce pulses for thyristor

the pulses need to be synchronised to the input AC voltage.

If I give a Phase angle,Labview should produce pulses at this phase angle.

say if I give 45 degree.the programme should prodce pulse for every 45 degree.

Plzz someone help me in this regard

-S.John Wesly

[Abhinav T]

John,

In order to help you better with this I would like to know what DAQ board you are using and which driver you are using to program this (NI-DAQ or NI-DAQmx)?

Thanks,

[John Wesly]

Thank you for ur concern.We don't have LabView 8 in our college.So Please reply  me back LabView 7.

Help me out this is my final year UG project.I got only 10 more days to finish it.. 

[Abhinav T]

John,

You can produce synchronized pulses with Analog Input using either LabVIEW 7 or 8 but I still need to know what Data Acquisiton card you are using and what DAQ driver you are using.

If you are using DAQmx there is an excellent example you can look at through the NI Example Finder (Help >> Find Examples... in LabVIEW). The example is called Multi-Function-Ctr Pulse Train Generation for AI Sample Clock.vi and you can find it by navigating to Hardware Input and Output >> DAQmx >> Synchronization >> Multi-Function in the example finder.

[John Wesly]

I Herewith attached my project.My problem is I don't get 50Hz pulse output in DAQ cord.PLz solve the problem and reply me back as soon as possible.

Thank you

-S.JohnWesly

[John Wesly]

Plz answer me.I'm getting 50Hz pulse in the program.But at the output i'm getting just 1Hz pulse.What might be the reason?

[Abhinav T]

John,

I looked over your program and I assume you are talking about the DAQ Assistant that outputs to the digital line.

The current setup you have performs a software timed write to the digital port and as such the timing of the output waveform is entirely determined by LabVIEW and any other process that is running on your PC at the time.

Here are a few suggestions on how you can improve the timing of your digital output:

- Improve your LabVIEW code that it either takes up less time per iteration or uses a producer consumer structure to have a more accurate loop time for digital writes
- Use hardware timed digital output - this is only possible with M series boards and you will have to create an external timing source using a counter
- Use a counter PWM output instead

Please let me know which one is a more viable option for you.

[John Wesly]

Sir,

Improving LabView code.Does it mean that I should use LabView 8.2

I don't have Idea on third option.

I'm new to LabView.

Plz excuse me.

-JohnWesly

[Brian F.]

Hello John. 

When Abhi mentioned improving your LabVIEW code, he meant that you could redesign your code to make it more efficient.  This would improve the speed of your digital output.  This doesn't require upgrading LabVIEW, but rather using a different architecture or using different VI's that will optimize your output. 

In order to help you out effectively, we still need to know which DAQ card you are using and what version of our DAQ driver you are using.  The DAQ card should have a label on it that reads something like PCI-6251 or USB-6008.  The first 3 letters will indicate what interface the DAQ card is using (PCI, PXI, USB) and the 4 numbers following will indicate things such as resolution, speed, and the number of channels available on the card.  Secondly, the DAQ driver is important because there is different functionality offered in different drivers as well as different versions of that driver.  You can find out which DAQ driver you are using by opening Measurement and Automation Explorer (MAX).  This can be accessed by clicking Start>>Programs>>National Instruments>>Measurement and Automation.  Once this program is launched, there will be a configuration window on the left hand side with a directory tree structure.  Please expand My System>>Software.  You should see either NI-DAQ or Traditional NI-DAQ  .  By clicking on one of these, you will see a version number in the main window of MAX.  Please respond with this information. 

Assuming that you are using DAQmx, I would recommend checking out the following websites which should get you started on programming in DAQmx. 

Learn 10 Functions in NI-DAQmx and Handle 80 Percent of Your Data Acquisition Applications
http://zone.ni.com/devzone/cda/tut/p/id/2835

NI-DAQmx Express VI Tutorial
http://zone.ni.com/devzone/cda/tut/p/id/2744

Let us know the information requested and we will be happy to help you further. 

Brian F
Applications Engineer
National Instruments

[John Wesly]

The Ni-DAQmx device that I am running is a PCI-6014 and have a BNC-2120 connected to it.  I am running Windows XP on my computer  NI-DAQ 7.1 and Labview 7 express.