Downlink — get the LoRaWAN class of a device

Returns the LoRaWAN class of a device: A, B or C. The class determines when the server can deliver a downlink: to a class A device only right after its next uplink, to a class C device at any time. Request the class before sending data to know how long delivery may take.

Request and response: dev_lw_class_req → get_devices_resp.
Access: a low access level token sees the devices of its application and of applications that granted it access; a high access level token sees all devices of the owner.

Current ONS version

The server responds with get_devices_resp, not dev_lw_class_resp as stated in the v0.17 description. You can tell this response from the response to get_devices_req by the lwClass field and your operation_id.

The server returns at most one device per request, so always specify devEui.

Request

Fields not marked as required may be omitted.

Field	Type	Description
cmd	string	dev_lw_class_req
operation_id	string	Any string; the server returns it in the response to match the request and the response
devEui	string	Device DevEUI, 16 hex characters. Without it the server returns one of the available devices — see "Current ONS version"

{
    "cmd": "dev_lw_class_req",
    "operation_id": "axd",
    "devEui": "6F1E570FFE14DBFC"
}

Response

Field	Type	Description
cmd	string	get_devices_resp
operation_id	string	Value from the request
status	uint8	1 — success, 2 — error
deviceCount	uint32	Number of devices in the list: 0 or 1
deviceList	array	Devices: devEui, devAddr and lwClass — LoRaWAN class (1 — A, 2 — B, 3 — C)
error_code, error_text	uint8, string	Only on error, see below

{
    "cmd": "get_devices_resp",
    "operation_id": "axd",
    "status": 1,
    "deviceCount": 1,
    "deviceList": [
        {
            "devEui": "6F1E570FFE14DBFC",
            "devAddr": "78130AE1",
            "lwClass": 1
        }
    ]
}

Errors

error_code	What happened
3	Invalid data in the request, e.g. devEui is not 16 hex characters
0	Internal server error — retry later

A device that does not exist or is not available with your token is not treated as an error: it is simply absent from deviceList.

See also

• Sending data to a device — how downlink works and in which order to call the commands.
• Device classes — how classes A, B and C differ.