Should class C downlink only use RX2 and not RX1

End Devices (Nodes)
1

Dear All,

I have an electric meter which implements class C lorawan end node device. My doubt is that if I want to send downlink data from lorawan network server to the electric meter via the RAK831 gateway, do I need to send it in RX2 frequency? Is it a specification in LoRaWAN that for class C end node devices the frequency used for downlink data should be RX2 and RX1 should not be used for sending downlink data?

Best Regards,
Sritam Paltasingh.

2

TTN doesnt support Class B or Class C operation at this time.

3

Ok. But still I want to know what the LoRaWAN specification says about the frequency to be used for downlink data in Class C end node

4

Then you need to read the specification…

1 Like
5

Now I confirmed that in LoRaWAN, if the device is in class C mode then the downlink messages from network server are sent in RX2 frequency. This is what the LoRaWAN 1.0.2 specification says.

6

Not really.

It is correct that if you want to leverage the “class-C ness” then you would send with RX2 settings.

But class C nodes still support RX1 after they uplink, just as class A nodes do. Should you happen to transmit during the RX1 window with RX2 settings, you would not be received.

1 Like
7

Yes, you are right. During transmission it will still have properties of class A. For eg: After 1 second of transmission completion(this time is configurable) RX1 slot opens and here the node will expect data in the RX1 frequency and SF which is the same as the frequency and SF which it used during transmission. At all other time when receive window is open, it will expect data to receive in RX2 frequency at a configured SF.
Thanks for the clarification.