3 - Receiving Messages
Messages sent from a network server to an end device are referred to as downlinks. These are sent to the end device via a single gateway. If there are multiple gateways near a device, the network server will select the most suitable gateway to broadcast from. This means the end device does not need to consider de-duping.
Devices operating in Class A mode only receive downlinks during the receive windows opened following an uplink, as described in the section Opening Receive Windows of the Sending Messages Book.
Devices that support Class B mode as well as Class A can receive additional downlinks in receive windows opened at fixed time slots. Read more about Class B mode in the Class B Book.
Devices that support Class C mode as well as Class A can receive additional downlinks at any time. Read more in the Class C: Continuously Listening for Downlinks book.
Todo
Fix link
In this book, you learn how to receive and handle downlink packets using the LoRaWAN® 1.0.4 specification.
Processing the Downlink Packet
Process the Application Data
When coding your application, you will identify several scenarios that require a downlink, such as changing settings, frequency of broadcast, or triggering a real-world action such as opening or closing a valve. You can assign each of these a different FPort value, between 1 and 223, and select an encoding method. The end device must use these rules to interpret the FPort value and decrypted FRMPayload value and take the relevant actions. Learn more about designing configuration by downlink in our paper Downlink Configuration Versus Firmware Version.
If either the port or payload cannot be recognized, the message must be ignored.