I don’t understand why my ABP devices can’t receive downlink, although after joining them over OTAA they can.
I have 2 different devices that work normally when joined over OTAA, but after adding them over ABP, ADR does not work(because they can’t receive downlinks).
Can someone confirm that all ABP devices can’t receive downlinks, or is it end device problem?
We have sent down links to abp devices for many years. If adr works I don’t know.
You need to check a few things:
- first off, track the packets in CS to make sure that you are seeing Downlink Packets being sent from the Network Server to the Gateway (and hence to the node). If you are not seeing any donwlink packets at the Gateway, double check all your node settings. If you see Downlink packets being sent, see the next steps
- make sure that the Loa WAN MAC version in the Device Profile matches the version used by the LoRa WAN Modem in your node. Incorrect MAC version will cause device Nonce errors to show in the Downlink packets
- make sure that the RX1 delay setting in Chirpstack matches that in your node (some nodes are hard coded for 1 sec RX1 WIN delay. In OTAA, the Join delay is 5 sec, and the RX1 delay is sent to the device during the join. If CS has been set to 5 sec RX1 delay and the node is expecting 1 sec, it will not work in ABP mode but will work in OTAA
- check that the Data Rate Offset (DRO) is the same in the chirpstack-network-server configuration file and in your device profile. This controls the data rate used in the downlink. If the offset is wrong, the device will not be able to receive the downlink. CS allows you to set a DRO in the device profile but then overwrites it with the setting from the toml file. If you see a device receive a downlink once but not again, this may be the cause