# Technical FAQs

### How to send data to Ubidots?

Ubidots accepts [HTTP](https://docs.ubidots.com/v1.6/reference/http), [MQTT](https://docs.ubidots.com/v1.6/reference/mqtt), [TCP](https://docs.ubidots.com/v1.6/reference/tcp-udp), and [UDP](https://docs.ubidots.com/v1.6/reference/tcp-udp) payloads. To learn how to send data using each of these protocols, refer to our [Data API documentation](https://docs.ubidots.com/v1.6/reference/welcome).

{% embed url="<https://docs.ubidots.com/v1.6/reference/welcome>" %}

### Can I control a device using Ubidots?

In theory, you can program a device to act based on changes to an Ubidots variable. You can do this either by polling the cloud at regular intervals or by [subscribing to a variable using MQTT](https://docs.ubidots.com/v1.6/reference/subscribe).

In practice, we only recommend using downlink commands to push configurations to remote devices, or, put differently, to perform "virtual controls." Physical controls are technically possible, but they pose a major risk when communication fails.

See some examples of virtual versus physical controls:

| Control Type         | Examples                                                                                                                                                                                                                                                                                        |
| -------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 👍 Virtual controls  | <ul><li>Change the update frequency of a device.</li><li>Reboot a device remotely.</li><li>Command a device to download new firmware from a specific URL.</li></ul>                                                                                                                             |
| ⚠️ Physical controls | <ul><li>Open or close a water valve. <strong>DANGER: If the "close" command is not received, a flood might occur.</strong></li><li>Start or stop a production line. <strong>DANGER: If the "start" command is received during a maintenance window, an accident might occur.</strong></li></ul> |


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