Can someone explain to me about this uplink message? Apparently there are 2 “LinkADRReq” in the message with different parameters. Please help. Thanks!
Below is an explanation for both LinkAdrReq commands that you have inquired about that will help to explain each section of the downlink in question:
Acknowledgement of Confirmed Uplink seqno 236
Per the table below from the LoRaWAN Regional specification, the first LinkADRReq command performs the following function: The ChnlCntl value of 7 disables all 125kHZ channels and then applies ChnlMsk of 0100 which enables the first 500 kHz channel: 64 (0000 0001)
For the second LinkAdrReq, the ChnlCntl equals “0” meaning it applies to channels 0-15 with the first 8 being enabled.
To further illustrate: To enable the entire bank of 16 channels the first ChannelMask would be 0300 - 0000 0011) - So, the full command would look like - LinkADRReq ChnMsk 0300 ChnlCntl=7, LinkADRReq ChnMsk=FFFF ChnlCntl=0
In addition, the Data Rate, Tx Power, and NbTrans values from the last LinkAdrReq (second in this case) command are what is enabled by the device
As an additional note the LoRaWAN 1.1 Specification and 1.1 Regional specification which provide additional detail, can be requested here:
Relevant information from the LoRaWAN Regional Specification