Before connecting wires or cables, make sure that the transmitter is powered off. Open the 2 hex screws on the cover of the transmitter using a 4-mm Allen key. Open the transmitter cover. Connect the wires inside the refractometer. For more information on connecting the refractometers, see PR53 Series User Guide (M212898EN) available at docs.vaisala.com. Connect the wires inside the transmitter, see Probe connection terminals and lead-throughs.