Using the RTSI feature of National Instruments' E-Series, analog output, counter/timer and 653x digital boards, you can synchronize various types of Data Acquisition. You can find more about synchronization by searching zone.ni.com with "synchronization". The third hit (Understanding Timing, Triggering and Synchronization) is good presentation that covers several timing issues. The actual synchronization of NI devices is accomplished via the RTSI bus. PLL just locks a particular oscilator to a reference (does not mandate synchronization.) For examples of how to synchronize input and output on an E-Series board, search the Developers Zone for "synchronize e-series."
Nick Wilson Application Engineering National Instruments www.ni.com/ask
"Nick W." wrote: >I want to replay a file in synch with data acquisition.>>I was thinking of a phase locked loop.>>
If you aren't talking high speeds you might want to read your file in and store it in an array. Run the array to your data acquisition loop and where the array enters the loop right click and enable indexing. You will read a set of data every time you collect new data.