64 User Guide—Figure 46 The Calibrate menuChanging the empty/zero valueThis value (probably set initially from the Easy Setup menu) represents the lowest level measurementvalue in your vessel. If you set this value first with the Easy Setup menu, you can change it later.To set this value:1 Select Calibrate > Level Calibration > ↓ Empty/Zero.2 Press Edit.3 Set the value as necessary and press OK.NOTICEMake sure that the empty value is less than or equal to the full value.Changing empty/zero value in hardwareTo set this value in hardware, you first need to completely empty the vessel whose level you want to measure.Once the vessel is empty and you have inserted the probe in the vessel:1 On the instrument head, unscrew and remove the nameplate. This exposes two buttons (identified Zand S) and the write-protection screw.—Figure 47 Accessing the Empty/Zero and Full/Span buttonsNameplateFull/Span (S) buttonEmpty/Zero (Z) button2 Once the probe is fully deployed in the vessel, press the Z button for a few seconds. This sets theempty/zero calibration value.