How to generate a square signal with SCXI-1124

[digitxm]

Hello,

I am trying to generate an analog output signal using labview. I would like it to resemble a square wave, but with the duty able to by modified (for instance, on for 10 seconds, off for 90, or on for 20 off for 80). I have two devices available for me to use. I have an NI USB-6008 which (from what I understand) is not able to accomplish this pulse generation due to the lack of a hardware counter. Is that correct?

I also have an scxi-1124 available to me. Would this be able to accomplish the task?

I would appreciate any help or direction to sample vi's anyone could give.

Thank you

[Ali M]

Hello digitxm,

Since the hardware you have is the limiting factor, with the NI 6008 you can perform a software timed pwm output if timing in your application is not critical (your cycle time is in the seconds range and you do not mind some milliseconds of delay) you can use a digital output with software timing control for your PWM generation. Also, see how to use AO channel(s) to control the voltage level of a square wave output (period of the square wave can be varied). Otherwise, this can be accomplished by using the following example on generating a digital waveform using non-regeneration in order to update frequency and duty cycle on-the-fly using National Instruments M Series or X series DAQ devices.

Best regards,

Ali M

Applications Engineer

National Instruments

[digitxm]

Ali,

I may end up purchasing an X series. What was the example you mentioned (link)? I will give the software timing a try and see if it is precise enough for my application. If not, I will be moving to the X series and would appreciate that example.

Thank you

[Ali M]

Hello digitxm,

The X Series is an excellent choice.

Example: Generate Multiple Channels of Digital Output with Different Frequencies and Duty Cycles

Best regards

Ali M

Applications Engineer

National Instruments

www.ni.com/support