Main Features：
1. Measurement of import/export active energy, current energy balance, instant 
    voltage, current, power.
2. Pre-payment function, and prepayment is loaded through 20-digit token
3. Tariffs function: support TOU tariffs and step tariff
4. Load control function Load limit configurable.
5. Events detection and record function, include cover opening, reverse, overload etc
6. Remote switch control functions: remote switch disconnect/ reconnect.
7. Message alarm function: the meter will inform users By sending message if 
    disconnect when energyReaches zero or power overload etc.
8. RTC:  clock with calendar, timing,leap year Automatic conversion function.
9. Alarm by LED/Buzzer when low credit , overload, tamper.
10. Relay control: 
     (1) the internal relay will be switched off when the top cover is opened 
     (2) overload 
     (3) out of remaining balance
     (4) RTC battery power down