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.
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
Change the update frequency of a device.
Reboot a device remotely.
Command a device to download new firmware from a specific URL.
⚠️ Physical controls
Open or close a water valve. DANGER: If the "close" command is not received, a flood might occur.
Start or stop a production line. DANGER: If the "start" command is received during a maintenance window, an accident might occur.
