LoRaWAN Downlinks | HydroNode

01How it works

Two directions through your network server

Your device talks to a network server, and the network server talks to HydroNode. Uplinks travel from the device through the network server to your HydroNode webhook. Downlinks travel the other way. HydroNode hands them to the network server, and the network server sends them right after the next uplink of the device.

Most LoRaWAN devices only listen for a moment after they have sent something. A downlink therefore never arrives at once. It waits at the network server until the device sends again.

Direction	What it carries	Where you set it up
Uplink	Measurements and status from the device.	A webhook in your network server that points at HydroNode.
Downlink	Commands, send intervals and battery thresholds for the device.	Downlinks in your HydroNode profile, with a key from your network server.

02What you can send

Station settings, raw bytes and shortcuts

Station settings

A HydroNode station with firmware 2.1 takes a new send interval and new battery thresholds. Change them in the sensor settings under On the device, or in Fleet with Change config. The station confirms the change and reports its values.

Raw downlinks

Send any bytes on fPort 1 to 223, up to 51 bytes, confirmed or not. Use Send downlink on the sensor page, or type the fPort and the bytes in the console, for example 2 11.

Station shortcuts

Stations come with ready commands: Clean SPS30, Request diagnostics and Restart.

Delivery you can follow

Every downlink shows whether it is queued, sent, acknowledged or failed, in the command history and in the console.

Owners and people with an Admin share can send downlinks. HydroNode accepts 20 downlinks per minute for each sensor and keeps at most 16 waiting.

03Set it up

Connect your network server first

Both networks need the uplink webhook first, because a network server only sends a downlink after an uplink.

TTN

The Things NetworkAllow the TTN key, add a downlink API key to your webhook, test and turn on.

Downlink API keyWebhook

ChirpStackCreate an API key, enter the connection in your profile, test and turn on.

API keygRPC-Web or REST

04After setup

Follow every downlink

Every downlink shows its state in the command history of the sensor and in the console.

State	Meaning
Sending	HydroNode is handing it to the network server.
Queued	The network server has it and sends it after the next uplink.
Sent	The network server sent it to the device.
Acknowledged	The device confirmed it.
Failed	The network server or the device refused it, and the reason is shown.
Expired	It was not sent within 24 hours.
Cancelled	You cancelled it before it reached the network server.

What you can send, from station settings to raw bytes on any fPort, is described in the LoRaWAN guide. Battery thresholds are explained in Battery and Power, and changes in Fleet in Fleet.