Newbie needs help with PWM, DAQ, good reference guides, and life

[Salvador_Santolucito]

Hi Eric,

Why don't you try out this example. It is based off of the shipping example "Cont Gen Voltage Wfm-Int Clk-Non Regeneration." It continuously generates an analog waveform without regenration. That means that it requests new data from LabVIEW instead of recycling the onboard buffer. You can change the duty cycle of the output on the fly.

-Sal

[labview1958]

I am also interested in your PWM VI. I am using a 6025E DAQ card. I have attached a sheet regarding the 50 PINS. Does the output comes out in ANALOG form? If so which pin is suitable? Do I need to connect to the ground pin?

[AnujD]

You would use on of the DACXOUT pins. Yes, it is analog, and it would be referenced to any of the grounds on that connector.

Regards,
Anuj D.

[DFGray]

I would not recommend using a buffered output for your PWM output. This will introduce a delay in your control loop and cause you more headaches than you care to think about. Use one of your general purpose counter-timers as a PWM output. The duty cycle can be changed on the fly without restarting the pulse train. Your delay will be one pulse cycle, at most. Check the NI-DAQ examples for how to do this. If the TTL level is not sufficient, buffer it externally.

[labview1958]

Hi DFGRAY

Are you recommending me to use a digital output terminal? I have decided to use the digital output rather than the analog output. By the way can you give me a very basic simple PWM.VI? I cannot seem to locate a simple PWM.VI that I can easily understand. I intend to use the PWM.VI to control an external circuit intended to supply a higher power to my dc motor. Obviously the digital output nor the analog output would be sufficient to power the dc motor.

[Kevin_Price]

I just searched ni.com for "PWM". One of the hits led to this example.

-Kevin P.

[labview1958]

I need to generate a digital PWM to control an external voltage source. I intend to control the external voltage from 0 to 20 volts with 0 to 2 amps of current. The IC i intend to use is TIP 41. Is that possible?

[Eric]

How do you increase the voltage of a counter output. My card is giving me about .5V. 5V would be a whole lot nicer. Any thoughts?

Eric

Ps PWM is working. We gave in and used one of the counters for the PWM.

[nimic]

Maybe a simple transistor + 5 V ref + pull-up resistor?

[Tobias]

Hello it looks like you have some more experience than I do. I guess my problem is similar to yours hence my question: How can I synchronize two output pulstrains that are generated on two counter outputs?
I can synchronize them at the beginning but the frequency and duty circle has to be variable. It is controlled by a control loop. When I change the frequency of the two output signals they are not synchronized anymore.
Thanks if you have any idea.
Best regards

Tobi