1. Backlight control Short press the key to turn on or turn off the backlight. 2. Reset Energy Long press the key over than 3 seconds can reset the energy. 3. Current Indication Current has direction indication, if there is -, it means the current is reverse direction, otherwise it is forward direction. Figure 2 Direction Indication 4. Energy Indication Energy 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 it 5. Working Mode Direct power supply: Direct supply by test voltage, test range is: 8-300V Independent power supply: Working voltage range is: DC5-12V, test range is:0-300V 6. Data Preservation Energy data and backlight state can be saved when power off.