Hello;
As long as the pH meter sends out some Analog voltage signal, you can use any of the DAQ example VIs Labview has.
A good one to refer to is the one called Continuous Acquisition and Chart(buffered).vi, which can be found at Search Examples->I/O Interfaces->Data Acquisition->Analog Input->Continuous Analog Input.
Just one more last tip, make sure to include the best range the input signal will have. By doing that, the DAQ board will apply the better gain in a sense the accuracy will be improved.
Hope this helps.
Filipe