> For the complete documentation index, see [llms.txt](https://docs.akenza.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.akenza.io/device-management/rule-engine/rule-actions/downlink.md).

# Downlink

Send a downlink to one or more devices when a rule condition is true.

A **downlink** action sends a command or configuration to devices when a rule condition is true. For example, close the blinds when the temperature exceeds a threshold.

Select one or more devices that use the same [data flow](/device-management/your-data-flow.md) as targets.

{% hint style="info" %}
Downlinks are supported for **LoRaWAN**, **MQTT**, and **CoAP** devices. HTTP devices cannot receive downlinks.
{% endhint %}

## Downlink fields

{% tabs %}
{% tab title="LoRaWAN" %}

<figure><img src="https://2165942204-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MMKXTFIN5ZlLOjBlfC4%2Fuploads%2FKTAaPb2DOtGpSZIwr08n%2Fscreely-1685093160937.png?alt=media&amp;token=da26205f-8d9e-4832-aa26-c60565d586b8" alt="A downlink action with port, confirmed flag, and payload fields"><figcaption><p>A LoRaWAN downlink action</p></figcaption></figure>

<table><thead><tr><th width="160">Field</th><th>Description</th></tr></thead><tbody><tr><td><strong>Port</strong></td><td>An integer.</td></tr><tr><td><strong>Confirmed</strong></td><td>Whether the device has to confirm the downlink.</td></tr><tr><td><strong>Payload</strong></td><td>A hex string. A JSON object is also accepted if the <a href="/device-management/your-data-flow/device-type.md">device type</a> has a downlink encoder.</td></tr></tbody></table>
{% endtab %}

{% tab title="MQTT" %}

<table><thead><tr><th width="160">Field</th><th>Description</th></tr></thead><tbody><tr><td><strong>Topic</strong></td><td>Optional. Appended to the downlink topic of the device. For example, <code>myTopic</code> publishes to <code>/down/&#x3C;secret>/id/&#x3C;deviceID>/myTopic</code>.</td></tr><tr><td><strong>Payload</strong></td><td>A JSON object.</td></tr></tbody></table>

The payload can use [payload templating](/reference/message-templating.md) to include data from the rule:

```json
{
  "key": "{{data.temperature}}"
}
```

{% endtab %}

{% tab title="CoAP" %}

<table><thead><tr><th width="200">Field</th><th>Description</th></tr></thead><tbody><tr><td><strong>Raw</strong> or <strong>Encoder</strong></td><td>With <strong>Raw</strong>, the payload is sent to the device as entered and the encoder of the <a href="/device-management/your-data-flow/device-type.md">device type</a> is bypassed. With <strong>Encoder</strong>, the device type encoder converts the payload first.</td></tr><tr><td><strong>Payload</strong></td><td>A JSON object.</td></tr><tr><td><strong>Confirmed downlink</strong></td><td>The device confirms delivery with a CoAP acknowledgment. Without it, the device has to confirm the command in a later uplink.</td></tr><tr><td><strong>Clear queue</strong></td><td>Removes all pending commands of the device before this one is queued. When off, the command is added to the end of the queue.</td></tr></tbody></table>

CoAP downlinks are queued. The device fetches pending commands when it wakes up, one command per request, and only over DTLS. See [CoAP downlinks](/device-management/your-data-flow/device-connector/coap.md#downlinks) for the delivery details.
{% endtab %}
{% endtabs %}


---

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