Documentation ABP Rx parameter

[disk91]

Hello, the Device Profile >> Join (OTAA/ABP) in ABP mode is not really clear and should be better documented:

• RX1 delay by default 0, is that 1s ? is 1 is 2s. We need unit and real value would be better
• RX1 data-rate offset not really clear definition too

Are the by default all 0 values work well ?

[brocaar]

This really depends how the ABP device is provisioned by the vendor. E.g. if the device has been provisioned with RX1 delay 3, then leaving this value to any other will break the downlink communication as ChirpStack will use the wrong delay when calculating the downlink receive-windows. The same with the RX1 data-rate offset. If you are using a different RX1 data-rate offset than that the device was provisioned with, then ChirpStack will use the wrong downlink data-rates.

The meaning of the RX1 delay and RX1 data-rate offset are specified by the LoRaWAN specs. In case of the RX1 data-rate offset, these are region specific.

I’m open to pull-requests how this can be better documented in the UI

[disk91]

thank you, the behavior is globally OK, it’s really more about what does 0 means, is 1 is 1 seconds or 2 seconds…

[brocaar]

This is how the RX1 Delay has been defined in the specs:

Thus 0 → 1 sec, 1 → 1 sec, 2 → 2 sec, …