... time, press once the zero calibration button. The LCD displayer will display:CAL1, with sound of the buzzer. ... 90°, press the button as step 1).The LCD displayer will display:CAL2, with sound of the buzzer. ... 90°, press the button as step 1).The LCD displayer will display:CAL3, with sound of the buzzer. ... 90°, press the button as step 1).The LCD displayer will display:CAL4, with sound of the buzzer. ...