multiple signals write to file timing discrepancies

[Turbine Kid]

I am using a NI DAQCard6024E with an SCC-68 connector block and LabVIEW 8.5. I am acquiring two analog voltage signals and one counter input to acquire frequency. When I write the three signals to one text file, import that into Excel, and analyze the data, the time data does not accurately match between the two voltage measurements and the counter input frequency measurement. The frequency time measurement shows greater time acquisition over the two analog voltage signals. I am lost as to what could be the problem? Could it be the analog voltage sampling rate and samples to read? Please see attached the VI and the Excel spreadsheet of data.

[Will_S.]

Hi Turbine,

The Frequency Measurement Task uses a counter to measure the number of ticks between periods of a signal. Because of this there is no acquisition timing Delta_X as there is with typical analog input tasks. So you can disregard the Delta_X = 1.0000 portion in the header of your LVM file for the frequency measurement. This 1.0000 value just seems to be default value entered for frequency measurements in order to maintain a consistent header.