[USB 6366] simultaneous analog reading

[Nocturn]

Hello,

I'm using the USB-6366 to measure two analog-signals simultaneously.

When I use one samplerate (while using a channel-list as physical Input) and the same

number of aquired samples for both of them togehter it works fine so far.

I got problems when I try to have them sampled both at different rates (and numbers of samples aquired).

(I tried this with two parallel DAQ-channels and therefore also two parallel Task-channels) 

The only way to get them read at different rates is to put them in a sequence and read them one after another.

- But I want to aquire the data simultanously (parallel) without using two devices. 

It's imprtant that the first value of channel A is taken at the same time as the first valuet from channel B.

(channel B should simply aquire the same signal at the same time with a higher resolution)

I assume there is a problem with shared clocks...(?)

Is there a workaround or even a solution? 

Thx in advance! 

[HoussamK]

Hi,

Thanks for posting your querstion in the NI Forum.

Neither multiplexed nor simultaneous X-Series cards allow for sampling at different rates on different channels.  These cards have a single analog timing engine so all channels on the same card are limited to one sample rate.

Independent sample rates are possible with the latest cDAQ chassis (e.g. the NI cDAQ-9174 and NI cDAQ-9178) .  These chassis have three timing engines, which means that we can have multiple (up to three) AI C-Series modules running within a single cDAQ chassis at different rates.

Another alternative would be to use one of the Reconfigurable I/O (RIO) FPGA based devices (e.g. NI PXI-7851R) which also allows for independent sampling rates on all of the available AI channels.

Regards

Houssam Eddine Kassri

NI Germany