Send a downlink
What is a downlink?
A downlink sends information toward a device or an HTTP destination. Use the device’s Downlinks tab to manage MQTT or HTTP downlink definitions.
A definition includes a name, a configuration and an encoder source used to prepare the request.
Configure and preview
Create the downlink and choose its transport
MQTT or HTTP.
Configure the destination and encoder
Set the topic or URL, and the encoder that builds the payload.
Select the outputs it uses
Set default output values where needed.
Preview before executing
Use the test and preview controls to inspect the generated request.
Check the destination, topic or URL, and payload carefully. The output names and values must match what the receiving device or service expects — the platform validates the shape of the request, not whether your device understands it.
Run a command
Use Run for the saved definition, review the output values and preview, then execute when ready. Check the returned result.
Successful submission is not confirmation of physical execution. A successful publish means the broker or endpoint accepted the message. Verify the device’s resulting state separately — normally by waiting for its next state report — before treating a command as applied.
This distinction matters most for anything with a physical consequence: opening a valve, starting a motor, changing a setpoint. Build your operating procedure around the device’s confirmation, not the platform’s acknowledgement.
Trigger on measurements
A downlink can be configured to trigger on measurements, executing automatically as readings arrive.
Test its encoder and destination manually first. Enable the measurement trigger only once you have confirmed that the generated request is exactly what you want, and only when automatic execution is the behaviour you intend.
An automatic trigger runs without further review. Verify the preview manually before enabling it, particularly for commands that actuate equipment.
When troubleshooting automatic execution, review the command results for the definition rather than re-running it by hand — the manual path and the triggered path can differ in the values they supply.