If you are able to increase the number of samples per time, you might get close enough to 2.7 and you can avoid interpolation. In this case, to make your VI work for any sample rate you should wire your waveforms dt-value as the step size for the cursor movement. This will make the cursor always stop at the first sample less or equal 2.7.
---- OK, writing this I received your VI ----> now slow down take it easy... Let's restart this
Do you want to use the cursor for visualization of the search process or was it just your first approach and you don't really need that cursor? If you only want to get a time value for that specific position in your waveform you can solve it in a more simple way.
If you want to stay with your method (for visual effects) you should use an free cursor and move it programmatic along the waveform samples. As soon as it reaches the "less or equal 2.7" point it stops at an interpolated x position for the y 2.7 value.
Please answer my question and I will try help you with a test vi.
