I am sampling an analogue signal at 500Hz using an X series Multifunction DAQ and a DAQ assistant function set to continuous sampling and a buffer set to 2, I then perform an RMS measurement on the sampled values using Amplitude and Level Measurement function. I filter this using a Filter function set to smoothing over a number of samples (moving average). All of these functions are contained in a While Loop. This all works fine. I now want to data log the moving average RMS value to file but not at the 500 Hz signal sampling rate but at 1 Hz, If I use the Write to Measurement File function there is no option to reduce the file write rate. I have tried using the decimate vi function to reduce the data array to a reduced number of samples per second but the Write to Measurement File function still writes at 500 Hz rate although a value only appears at the decimated rate, i.e. the file is still huge with lots of blank date/time stamp entries between values. I guess I need nested loops but I am not that familiar with this to do what I want. You would think this would be a common problem that lots of users come across but I cannot find a simple answer in the examples. Is there a Write to Measurement File type function where you just select the write rate in seconds independant of the data sampling rate?
