How do I set the low pass analog input filter (anti-alias) on my DAQ Setup?

[mea03wjb]

 I have read the following from the PXI-6251 manaual:

"On some devices, the filter cutoff is fixed. On other devices, this filter is programmable and can be enabled for a lower frequency. For example, the NI 628x devices have a programmable filter with a cutoff frequency of 40 kHz that can be enabled."

It doesn;t explain how you know this value. So I have the following questions:

1. How do I know what the cut-off freq is on my device?

2. How do I know if its programmable?

3. How do I programme it if it is programmable?

I am using the PXI 6251 in conjunction with the PXI 1031.

Many thanks.

[LucaP. · Accepted solution]

The PXI-6251 has no anti-aliasing/programmable filter.The small signal bandwith (-3dB) of the 6251 is 1.7 MHz.You'll find this informations in the specifications manual.

If you need a filter, then you've to add the signal conditioning yourself.

The 628x M high accuracy boards are the only M series boards with "programmable" low pass filter. Check this KB for more details.

Hope this helps.

Luca

[Hillman]

Hi mea03wjb,

I hope your well today.

I was wondering if the advise Luca gave you answered your questions - it does the KB answers them in very good detail, and if you require any further support?

Thanks for your post! 

[mea03wjb]

Hi,

Luca, thanks for your fast answer! It was all I needed to know, we are now in the process of building a programmable anti-alias filter for our test-rig now I know the 6251 does not have one.

Thanks again,

Will