You ignore the analog interface. The "nature" of the pH probe can be resistive, voltage or current based, and this is what an according analog circuit will have to provide to the meter. How many wires connect the probe and the meter?
You ignore the analog interface. The "nature" of the pH probe can be resistive, voltage or current based, and this is what an according analog circuit will have to provide to the meter. How many wires connect the probe and the meter?