Sine wave generation

[krithika]

Hi Dev

Thanks for all the help !!

I have  connected my SCXI to the CB-68LP terminal block with all the cable assembly.

Now using the VI attached i have been able to generate continuous sine wave that i will be feeding to an amplifier. I want to display the output from the amplifier (increased power) using LABVIEW. As i am new to LABVIEW i first tried using the analog input example and sine wave generated by my oscilloscope to see if i can read the analog sine input. I am having difficulties with it. I am not getting any readings.

What i am confued is whether i need to connect the output (from the oscilloscope) to the CB-68LP terminal block then connect it to the scxi or do i just connect it directly to scxi channel 0 (+,-)?? Also can you tell me whats the best example that i use for the same. (REMEMBER : I have traditional DAQ........ so all the more difficult)!

Pls help me out!

Also can you suggest what i can do in the Vi attached so that i can have control on the frequency??!!

Thank you so much for being so patient with me and my silly questions.

Best  Regards
krithika

[krithika]

OOPS  HERE is the VI !!

Thanks for all the help !!

I have  connected my SCXI to the CB-68LP terminal block with all the cable assembly.

Now using the VI attached i have been able to generate continuous sine wave that i will be feeding to an amplifier. I want to display the output from the amplifier (increased power) using LABVIEW. As i am new to LABVIEW i first tried using the analog input example and sine wave generated by my oscilloscope to see if i can read the analog sine input. I am having difficulties with it. I am not getting any readings.

What i am confued is whether i need to connect the output (from the oscilloscope) to the CB-68LP terminal block then connect it to the scxi or do i just connect it directly to scxi channel 0 (+,-)?? Also can you tell me whats the best example that i use for the same. (REMEMBER : I have traditional DAQ........ so all the more difficult)!

Pls help me out!

Also can you suggest what i can do in the Vi attached so that i can have control on the frequency??!!

Thank you so much for being so patient with me and my silly questions.

Best  Regards
krithika

[devchander]

Hey krithika,

First i would like to answer the last part of your query,

To control the frequency, all you have to do is toy around with the update rate, cycles per buffer  and the buffer length

For ex,  if cycles per buffer = 10 and buffer length = 1000, effectively, each sinusoidal oscillation in the generated waveform will be represented by 100 points.

Now  if update rate = 1000, then you will get a sine wave of frequency 10 hz on the selected AO channel.

in the same case, if you bring the update rate to 100, frequency of sine wave generated on Analog output becomes 1 Hz.

for going to higher sampling rates, take a larger buffer size, suitable update rate and increase number of cycles

Just keep in mind, lesser number of samples per cycle, poorer will the quality of your generated sine wave be.

so represent each sinusoidal cycle by suitable number of points.(practically i have observed that each sine wave represented by more that 20 points looks decent. but the fact is that more number of points, the better sine wave you get )

hope you get the idea.

so a buffer size of 10000, cycles per buffer 100 and update rate 10000 give a sine signal of frequency 100 hz.

check out the maximum update rate and permitted buffer size that the AO of your DAQ card supports to calculate the max frequency you can generate using this VI.

Regarding the first part of your question, I have these doubts.

• what cable are you using to connect your PXI-7030/6040E( Rt series) daughter DAq card PCI 6040 E to your SCXI Module?
•  What cabling are you using to bring the 6040 E series DAQ card's AI/ AO on to CB 68LP?

All the SCXI channels are multiplexed to the channel 0 of the DAQ card.So, you can use any other DAQ channel except channel 0 to read your generated sine wave. 

Use any AI examples to achieve this.

Previously, you spoke of using this sinusoidal output to run a motor, on which you have mounted the strain gages.

Now,  do you want to measure this generated sinusoidal output using any analog input on the DAQ card?

You cannot measure this sine wave on the scxi module's channels but you can measure it on the spare channels of PCI 6040 E, (if the singal is within the limits of the DAQ's ADC range)

Regards

Dev