GREEN LED D3 | RED LED D4 | Description 
-------------+------------+-------------------------------------------
OFF          | OFF        | Standby Mode 
1Hz FLASH    | OFF        | Upstream heartbeat frame
OFF          | FLASH      | Upstream Alarm Steam and Check angle value 
4Hz flash synchronosly    | Push button S6 
ON                        | Reset to default setting

RED LED D5 | Description
-----------+--------------------------
ON         | Connect to NB‐IOT network 
OFF        | No NB network