Measurement of pH value
Plug the sensor into the slot #4 (by default) and press keypad "8" to measure.

Hints on calibration of the pH sensor:
Need to calibrate the pH sensor to get accurate reading. After putting it into a buffer solution of pH=4, select Calibrate from the lower right menu (or press keypad "D#"). Then, rinse it with distill water and put it into another buffer solution of pH=10 for calibration again.