Is This Correct ... Sampling

[HowAli]

Just so it's clear in my mind, NI DAQ devices (driven by NI-DAQmx ?) sample in the following manner:

If you've got a max sampling rate of 250 kS/s and you've got say 10 channels, you're instantly down to a true (i.e. ignoring solutions which result in uneven distribution of samples) sampling rate of 25 kS/s max per channel. It doesn't matter if you want 100 kS/s on one channel and 1 S/s for all the others ... you can't do it. What you'd have to do in this particular example is go for a solution which offers 10 x 100 kS/s = 1 MS/s ? Is this right ?

Any advice appreciated as I need to make a decision on a purchase ... rapido !

[TV_Enable]

Hello,

Your overall understanding of National Instrument's DAQ devices is correct.  However, what you are saying is only true of NI's DAQ devices that only have one Analog-to-Digital Converter (ADC).  Because of this, the device has to multiplex through each of the channels, dividing the sampling rate of the device by the number of channels you are reading from.  

There are a few options you have.  Some M-Series devices, such as the PCI-6251, can achieve an aggregate 1 MS/s.  This would allow you to acquire from 10 different channels at 100 kS/s.  Another option you have is to use an S Series device.  S Series devices support simultaneous sampling; that is, each channel has its own ADC rather than one for the entire board.  The PCI/PXI-6123 device can acquire at 500 kS/s on each channel.  A lower-cost option is the PCI/PXI-6143, which can achieve rates of 250 kS/s per channel.  Both the 6123 and 6143 have 8 analog input channels.  See ni.com/daq to visit to filter through NI's DAQ devices according to your needs.

I hope this helps.  Have a great day!

Regards,

Todd V 

[HowAli]

Yes, that helps a lot. Thanks for advice.