How to generate voltage pulse with 200us duty cycle and 1000us period PCI6259?

[TrH_Linh]

Hi all,

I'm very new to LabView and DAQ. For my project, I want to create an analog voltage pulse with amplitude from 0.5V - 3.5V, duty cycle of 25% (period = 1000 micro second). Please guide me how to generate one
I'm using LabView 8.2.0 and PCI 6259.

Thank you very much

Regards,
Hai Linh

[Chris_D]

Hai Linh,

LabVIEW ships with many great DAQ examples. You can access these by going to Help » Find Examples in LabVIEW. The Cont Gen Voltage Wfm-Int Clk.vi should be a great starting point for you. In the Example Finder navigate to Hardware Input and Output » DAQmx » Analog Generation » Voltage » Cont Gen Voltage Wfm-Int Clk.vi.

Also, since you are new to LabVIEW and DAQ here are a couple great tutorials.

LabVIEW Introduction Course - Three Hours
http://zone.ni.com/devzone/cda/tut/p/id/5243

Complete Data Acquisition Tutorial
http://zone.ni.com/devzone/cda/tut/p/id/3116

[TrH_Linh]

Thanks Chris_D for your reply. Though, I can't find the Cont Gen Voltage Wfm-Int Clk.vi in >>Voltage. There are only 3 examples and all of them begin with Cont Acq&Graph Voltage.

Rgds,
Hai Linh

[TrH_Linh]

Hi,

Thanks for the help. I made a mistake and I have found the file. It worked with the square waveform, however, I have tried to play with it but still don't know how to change the duty cycle of this analog output voltage. The output voltage is always squarewave form
(link: http://edventure.ntu.edu.sg/bbcswebdav/users/tr0001nh/FYP/Vol-gen-ques.JPG )

I'd like to be able to change the duty cycle of this waveform to fit into my application. How could I change it? Thanks

[TrH_Linh]

Hi,
Another question related to this issue, when I set the wave-form to Amplitude of 1.25V - offset -0.75 its range is from -2V to 0.5V. However, when the signal come out from DAQ board and to osciloscope - it indicates a waveform of range from -1.1V to 1.4V. Could you advice me why is it so and how could I correct it? Thanks 🙂

[Chris_D]

Hai Linh,

To change the duty cycle you will have to modify the Waveform Buffer Generation VI in the example I showed you. To do this double click the the Waveform Buffer Generation VI block and it will open its block diagram. Next, look for the Basic Function Generator VI. This VI has an input for the duty cycle. You can either create a constant here for the duty cycle or wire a control to have it as an input on the original examples block diagram.

As far as the offset goes, where are you configuring this? This should be configured on the same Basic Function Generator VI as mentioned above. I was able to test this and received the expected results.

[TrH_Linh]

Thanks Chris,

I'm now able to generate the signal I wanted 😉