USB 6215 AO resolution

[Tomaz Lusin]

Hi all,

USB 6215 DAQ board uses16-bit analog to digital conversion. Is it possible here to set lower bit conversion e.g. that DAQ board works only with 12-bit A/D conversion on particular input analog channels. Thanks in advance for your help.

tommy

[e2m0i0l7]

Hi Tommy,

Could you please let us know why you would like 14 bit resolution, and why 16 bit would represent an issue?

Thank you,

Mircea

[Tomaz Lusin]

Hi,

I want change conversion resolution because I want to use 3-parameter sine-fitting algorithm to check A/D. Actually, I want to show how A/D resolution may affect measured signal in frequency domain. I know, sine-fitting methods are based in time domain, but also the same acquired signal I want to represent in frequency domain at different A/D resolution. But I seems to me that thica can not be set as easy way or not? Thank you for your replies on this.

Have a nice day,

Tommy

[e2m0i0l7]

Hi,

The resolution of the ADC cannot be phisically changed, as it is in HW.

On the other hand , the SW component is more flexible, so you could transform your 16 bit signal into 14 bit.

The easiest would be to make the two LSBs 0.

If I might have a recommendation, if you use LV for sine-fitting, have in mind the vi: Extract Single Tone Information.

Good luck,

Mircea

[Tomaz Lusin]

Thank you for the tip.I will try this.

Have a nice day,

Tommy

[John_P1]

Here is a link to a shipping example that shows how you can convert a DBL into a calibrated, unscaled binary number.  You'll probably want to modify it to use 16-bit numbers instead of 32-bit.

You can then use LabVIEW's And Function (it performs a bitwise AND on numeric inputs) to mask out the last two bits like Mircea suggested.  Assuming you modify the example to use 16-bit integers, you should use 0x FFFC (1111 1111 1111 1100) as your mask to set the last two bits to 0.

Best Regards,

[Tomaz Lusin]

Thank you,

that is I was looking for. Simple and efficient way.