Is the sample rate split among channels USB-6211

[aeson25]

I'm using a USB-6211 DAQ board.  The board is advertised with a 250kS/s rate.  I started taking measurements with 2 channels and could only get 125kHz sampling frequency, then when I tried to take measurements on 5 channels, I only could get a max of 50kHz sampling frequency.  Is that 250kS/s figure really the sum off all the channels, or is there a way to get that from each channel?  

I just have a simple Laview program with a while loop, 1 input DAQ assistant with the 5 channels, 1 output DAQ assistant with 1 output channel, "Trigger and Gate" box for catching a step input, a smoothing filter, and the graphs.

[johnsold · Accepted solution]

The 250 kS/s is an aggregate rate as stated on the first page of the specifications document.  This means that the device has only one A/D converter which is shared among all the channels being scanned.  Depending on th etime it takes for the multiplexer and any settling time for the internal amplifier, your maximum rate may be slighlty less than 250,000/N where N is the number of channels.

Lynn