You could use a wait function in a separate while loop and use a queue or local variable to pass the data from a main loop. You could also in your main VI use either Tick count or Get Date Time In Seconds. Initialize a shift register with a start time and inside the loop, get the current time, subtract the start time and see if its greater than your log interval. When it is greater, do the logging and set the shift register value equal to the current time.