sk_labVIEW,
A few things.
1. The progressing changes in your Phase Difference are going to be because you are using an M Series card, like was mentioned in a previous post. The single ADC means channels are multiplexed at a fast rate and sent through one sample at a time. This results in virtual simultaneous sampling, but not true simultaneous, which is why you see the changing phase difference I believe.
2. The error that you recieved before mentioned something about samples being read before they are are written. I believe that this is occuring in your File VI. You will notice that you have no data dependcy between you write to spreadsheet file and your read from file, so it is possible, that LabVIEW is calling the read before anything is written. It is good programming practice typically to connect the error clusters to enforce programming flow. However, these express VIs don't seem to have error clusters so, while not as desirable, you can use a flat sequence structure, as seen in the attached screenshot, and hopefully this will prevent this error in the furture.
Was there anything else that you were asking about?
Regards,
Mallori
Mallori M
National Instruments
Sr Group Manager, Education Services
ni.com/training
