Rejoin mode is a feature for every Milesight LoRaWAN end device to set up network connections automatically when LoRaWAN gateway or network server is abnormal. Rejoin mode is also the base to achieve data re-transmission feature to record the time of data lost. 


Method 1:

Login device configuration page via web GUI or ToolBox to enable the rejoin mode and set the number of detection (range: 4~32). Only when join type is OTAA, the rejoin mode can be supported.


Method 2:

Send downlink command from network server to disable/enable rejoin mode. Note that when you modify below settings, the device will rejoin the network immediately.

Rejoin mode off: 7e05090050da01007e

Rejoin mode on: 7e05090050da01017e

Set number of detection as 4: 7e05090050d901047e

Set number of detection as 32: 7e05090050d901207e

Working Mechanism

The device will start a link detection event every 25~35 minutes after device joined the network and last link detection event is completed. When the event starts, the device will send a LinkCheckReq MAC packet with next data uplink (periodic uplink, threshold alarm uplink, etc.). If the gateway and network server work fine, the device will receive the LinkCheckANS packet from network server; if the device does not receive LinkCheckANS packets continuously for preset detection times, the device will reboot to send join request to network server to try to rejoin the network automatically. The real detection times is N+1.

 Parameter definition:





Reporting interval of uplink

User Configurable


Link detection event interval

A random value among 25~35 mins


Number of detection

User Configurable


According to above mechanism, the time for rejoin mode to take effect can be calculated as below:

TR>35 minutes: TR* (N+1)

25≤TR≤35 minutes: max time = 2*TR*(N+1), min time=TR* (N+1)

TR<25 minutes: (TL+TR-TL%TR)*(N+1),TL=25~35



When reporting interval is 40 minutes and number of detection is 4, the max time to device rejoin is 40* (4+1)=200 minutes.

When reporting interval is 10 minutes and number of detection is 4, the max time to device rejoin is (35+10-35%10)*(4+1)=200 minutes, the min time is (25+10-25%10)*(4+1)=150 minutes.



  1. Milesight devices will send LinkCheckReq packets with Fport=0. This can be used to differ MAC packets and data uplinks.
  2. When you connect Milesight LoRaWAN end devices to Milesight IoT Cloud or gateway embedded network server, the gateway will not display the LinkCheckReq packet and occupy the fcnt.
  3. When device reboots or rejoin mode takes effect, it will send join requests to network server according to this interval: every 15s on first 32 packets, every 1 minute on 33~96 packets and every reporting interval on the last packets.