1. Backlight controlShort press the key to turn on or turn off the backlight.2. Reset EnergyLong press the key over than 3 seconds can reset the energy.3. Current IndicationCurrent has direction indication, if there is -, it means the current is reverse direction, otherwise it is forward direction.Figure 2 Direction Indication4. Energy IndicationEnergy has direction indication, if there is -, it means the energy is reverse direction, otherwise it is forward direction.The energy direction is judged according to the current direction, If the current is positive, the energy will increase, maximum is 999kwh, overflow will be maintained, unless you reset it; if the current is reverse, the energy will decrease, maximum is -999kwh, overflow will be maintained, unless you reset it5. Working ModeDirect power supply: Direct supply by test voltage, test range is: 8-300VIndependent power supply: Working voltage range is: DC5-12V, test range is:0-300V6. Data PreservationEnergy data and backlight state can be saved when power off.