Table of Contents:

• 1. introduction
• 2. What is the rejoin feature?
  • offline rejoining （LWS007)
• 3. Examples and Explanations
  • 3.1 Configure appropriate operation times

1. introduction

This chapter describes switch LoRaWAN server by rejoin feature.

2. What is the rejoin feature?

rejoin feature is that if the ACK packet sent by the platform to the node is not received within the set time range, the offline detection will be started.

offline rejoining （LWS007)

AT Command: AT+DDETECT

AT+DDETECT=<Flag>,<ACK_Timout_1>,<ACK_Timout_2> (Default Value: AT+DDETECT=1,1440,2880)

• ACK_Timout_1: Unit: min

• ACK_Timout_2: Unit: min

Downlink Command: 0x32

Format: Command Code (0x32) followed by 2 bytes mode value.

If the downlink payload=320105A00B40, it means set end node to use confirm mode, while type code is 32.

• Example 1: Downlink Payload: 320105A00B40                     // Set AT+DDETECT=1,1440,2880

• 
  
  • 0x01 : Flag

         0x05A0 : ACK_Timout_1 : 1440minutes (24 hours)

         0x0B40 : ACK_Timout_2 : 2880minutes (48 hours)

• Explain: Enable Online Detect, if end node doesn't receive any downlink within ACK_Timout_1( 1440 minutes or 24 hours). End node will use confirmed uplink to send packets during ACK_Timout_1 (the 24th hour) to ACK_Timout_2 ( the 48th hour). If from the 24th to 48th hour, end node got an downlink from server, it will switch back to unconfirmed uplink. end node will restart ACK_Timout_1. If from the 24th to 48th hour, end node still not got any downlink, means device doesn't get ACK from server within last 48 hours. Device will process rejoin, rejoin request interval is AT+RJTDC period. For AU915/ US915, device will use the sub-band used for last join.

3. Examples and Explanations

Switching platforms by rejoin function: Use device LHT65N to switch from TTN to ChirpStack as an example.

The following example shows the parameters of the LHT65N. Users need to check the Wiki instructions to confirm the parameters of the equipment they have purchased.
(User Manual for LoRaWAN End Nodes))

3.1 Configure appropriate operation times

Firstly, the user sent downlink commands through the original registration platform (TTN) to modify the required TDC time and offline detection time.