# Downlinks
The **Downlinks** tab allows you to configure and add downlinks. Once created, each downlink can be sent manually to the device.
To add a downlink, click on the **Add Downlink** button. The **Add Downlink** modal opens.
In the **Name** text box, enter a **name** for the downlink.
In the **Comment** text box, enter additional details about that downlink.
There are two options that you can enable by turning on the following toggle buttons:
* **Pass payload data to downlink** - pass the last uplink payload to the downlink.
* **Activate after uplink** - send the downlink after receiving an uplink.
The downlink payload can be configured using either the **Default** or **Custom** options:
**Default**:
In the **Default** tab, you can configure the downlink payload by providing suitable values for each data field. When you enter values, make sure that they are in the valid range and type.
{% hint style="info" %}
These data fields appear in the Add **Downlink** model box only if they have been added to the **device type** under the **Downlink Data**. To ensure the correct functioning of the downlink, a valid **downlink payload formatter** must also be added to the device type under the **Downlink Data.**
{% endhint %}
Click on the **Save** button.
**Custom**:
In the **Custom** tab, you can write a custom **downlink payload decoder**, for example, something like this.
```
function decode(payload, params) {
const red = ('00' + payload.red.toString(16)).slice(-2)
const green = ('00' + payload.green.toString(16)).slice(-2)
const blue = ('00' + payload.blue.toString(16)).slice(-2)
const on = ('00' + payload.on.toString(16)).slice(-2)
const off = ('00' + payload.off.toString(16)).slice(-2)
return ${red}${blue}${green}${on}${off}
}
```
Click on the **Save** button.
Once added, the downlink will be displayed in the **Downlinks** tab. Similarly, you can add more downlinks that can be used to control different functionalities of a device.
Click on the **Send** button to send the downlink to the device.
---
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