Figure 1. Connection diagrams of electrodes to pH meter.
Comb.el - combined electrode; G - grounding electrode; Rt - temperature sensor;
H – housing; A – Auxiliary electrode In; M – measuring electrode In.

Figure 2. Connection diagrams Resistance thermometer (Temperature sensor Rt)
a) - two-wire; b) - three-wire.

Figure 3. Connection pH meter to the power supply

Figure 4. Diagrams of external connections of devices with current output

Figure 5. Scheme of the pH-meters connection in the Modbus network