Downlink message and timing


I’m struggeling a bit with my testing of Chirpstack. My setup is for now one gateway and one sensor. The sensor reports data as it should but I’m struggeling with the downlink. When I generate a downlink-message it dissapears from the queue right away. My device wakes up and sends data once every hour so I expected the downlinkmessage to be queued until wakeup.

In the downlinkmessage I see timing:“IMMEDEATELY” and I suspect this is why my downlink is not queued? But I cannot find out how to set this parameter.

Here is a screenshot of the downlink-message:

Are downlinks working on Chirpstack ???

I’m facing an issue where i can’t receive join accept downlinks on my sensors, I’ve seen multiple topics about this…

You probably have setup the device profile as class c, so the network server sends the downlink message immediately.

In fact, the downlink message is being sent through the default rx2 window: frequency 869525000 and SF 12.

You could check up your lora packet forwarder in the gateway to see if messages are arriving and what it is doing with them.

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Yes, they work really well

I think this is indeed very likely the case.

Ok. I will try to look into the logs on the gateway. @pulidoj you mention class C in device profile. I have checked with the vendor and they say that the sensor only support Class-A.

Vendor-info is:
MAC Version: 1.0.2
Regional Parameters: Rev B
Device Class: Class-A

So why do I need to activate class-C support on the device-profile?


Perhaps I didn’t explain completely.

I suggested that perhaps you had enable the Device Profile as class C.
If that was the case, the Network Server will send the downlink message Immediately, and on frequency and SF selected on RX2.
If class C is not selected, then the Network Server should send the message as DELAY and with the same frequency and SF received in the uplink.

In the part of the sensor, if it is setup as class A it will open the reception window only after transmitting an uplink, otherwise it is always listening to the Network Server.

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