12-28-2013 11:18 AM
hi
i am working on LV 2012 with PCI 6221.i just wanna know the concept of hardware clock and software clock,internal clock and external clock.
is harware timed single pointsample mode in DAQmx timing VI take DAQ board clock or CPU clock?
vks
12-30-2013 06:29 AM
The PCI-6221 has a built-in clock that it uses to read/write samples at whatever rate you tell it. For example, you want to sample a signal at 1kHz. That is a hardware clock. This data is stored in a buffer on the board.
A software clock is not really a clock. It is just whenever the software tells the DAQ board to give it a sample, the DAQ board takes a sample.
The hardware clock is a lot more reliable and deterministic. So you use a hardware clock when the timing is critical. Use the Finite Samples or the Continuous Samples mode to use a hardware clock. If you just want a single sample at some random point in time, then just use the single sample mode.
The CPU clock is not really in the picture other than the fact that the CPU processes the commands in the software.