What is the meaning of buffer and How to use buffer

[Yun_Zhu]

Could you tell me What is the meaning of buffer and How to use buffer

[BenDAE]

Yun_Zhu,

Would you mind telling me a little bit more info? At a very high level: there are lots of types of buffers: the DAQ itself has a buffer, the device driver for the DAQ has a buffer, and you can even create additional buffers in your labview program.

A buffer is a place to store data until it can be processed. Buffers are used when data is being created faster than it can be processed. As an analogy think of a bank. Ideally, you don't spend your money as fast as you get it. Every payday you get a lot of money, then you spend the rest of the time spending it little by little. The bank in this case is a buffer for your money.

Hope this gets you started!

[Yun_Zhu]

In this vi,

1.What's the meaning of samples per buffer?Cycles per buffer?

2.Why the value of sample rate is much smaller then the value of sample to read?What is the relationship between them?

3.Does the  samples per buffer or Cycles per buffer has any ralationship with other parameter in front panel?

4.Could you tell me about buffer according this vi?

[Matt.M]

Hi Yun,

The VI you are asking about for question 1. you did not include, so I do not know what "Samples Per Buffer" or "Cycles Per Buffer" means.  You should probably ask the creator of that VI.  I would guess it means for each round of waveform generation how many samples to create and how many periods of the waveform to include.

2.) The value of the sample rate is much higher than samples to read.  Sample rate specifies the sampling rate in samples per channel per second. The samples to read specifies how many samples to read from the buffer per loop iteration.

3.) I can't answer that as the VI is not included, I would recommend asking the author of that VI.

4.) It looks like the VI's you did not include create a waveform to put in the buffer for an Analog Output task.  The buffer is memory that holds values that will be output by the hardware.  In the context of those VI's I'm not sure what Samples or Cycles per buffer refers to.

Regards,

Matt M.

[Yun_Zhu]

Hi Matt,

You could see the vi in attachment.Do you need I send you again?

Thanks

Yun 

[Matt.M]

You did not include the two custom sub-vi's that are used in the main VI.  I think I answered your questions as well as I could, even if I had the other two VIs though.

Regards,

Matt

[Yun_Zhu]

I am sory I didn't.Did you mean the two subvis in attachmennt?