PCI-6225

[albartp]

Hello,

I have to sample 80 signals. The PCI-6225 is said to manage this at 250kS/s.

- But is 250kS/s the maximum frequency reached when only 1 channel is used ?

- If yes, what becomes this frequency when all the 80 channels are multiplexed ?

Thanks.

[WM_John_Weeks]

You are correct that 250 kS/s is the total sample rate. For 80 channels, the maximum sample rate is 250000/80=3125 S/s.

[albartp]

Yes I know this. The total (aggregate) amount of S/s is divided by the number of channels to obtain the amount of S/s/channel.

But I was only talking about the total (aggregate) amount of S/s. Is this quantity not reduced too when the multiplexor is running, because of some additional delays (interchannel delay, the interscan delay (1 scan = 1 reading of all channel), settling time, ...) ? Is this quantity not reduced too when increasing the accuracy (the more accurate, the more the settling time too) ?

Thanks.

[WM_John_Weeks]

That kind of information would be in the specifications. You can download the specifications document here:

http://digital.ni.com/manuals.nsf/websearch/D46066EF4005E18B862570190078B514?OpenDocument&node=132090_US

[thomson]

The maximum sampling rate of the PCI-6225 is 250 kS/s regardless of the number of channels scanned.

[Dr._Imad]

But because channel scanning is multipled with the same clock, the scan rate is 250kS/s  / # of channels.

Your statement is true for the S series cards, where each channel has a dedicated clock.