usb-6343 digital input sampling rate

[goshinskiy]

Hello, friends!

I've got a problem with understanding the technical information of my USB-6343 DAQ.

I need to know the exact sampling rate in case of digital input, but i can find only analog input sampling rate. Or is it 500 kSample/s for both digital and analog signal?

There is some info for Digital input: 

Internal base clocks 100 MHz, 20 MHz, 100 kHz
External base clock frequency 0 MHz to 25 MHz

Phase-Locked Loop

reference clock locking frequency - 10 MHz

Can you please explain what does it mean?

Thanks!

[Kevin_Price]

The most relevant spec is listed under the "Waveform Characteristics" section of the DI/DO specs.  Specificially, sample rates up to 1 MHz are supported by the device, though whether or not you can *sustain* that sample rate indefinitely is "system dependent".   That's a pretty typical caveat with USB-connected devices.

Note that sample clocks are generated by dividing down the default timebase of 100 MHz.  So you'll only be able to get sample rates that are integer divisors of 100 MHz *and* <= 1 MHz.  (In other words, you can divide 100 MHz by integers >= 100.)

   The driver figures a lot of this stuff out for you.  When you request a sample rate that can't be generated exactly with an integer divisor, the driver uses one of the near neighbors.  I *think* it will typically use the next lower divisor, yielding the next higher sample rate.

-Kevin P