# Overview
Commands are used to get information from the IoT-device and send configuration data to it.
Commands can be send via a JSON string or a “command line interface” (CLI) like string.
## Commands in JSON-Format
JSON commands have the folloging elements:
| Key | Comment |
| - | - |
| CMD | Command |
| IDX | (optional) Index of an instance |
| SRC | (optional) Source of the request for autentification |
| params | (optional) Parameters to transport |
| xxx | (optional) Additional argument for the command |
Example:
```JSON {
'CMD': 'gadget.setparams',
'SRC': '127.0.0.1:55555',
'IDX': 1,
'params': {"Lorem":1, "Ipsum":2}
} ```
## Commands as CLI
TODO
`variable.set <key> <value>`
Examples:
`variable.get pi`
`variable.set pi 3.14`
`variable.set mystr “Lorem Ipsum”}`
`variable.set mylist [“Lorem”, “Ipsum”, 0, 8, 15]`
`variable.set mydict {“Lorem”:1, “Ipsum”:2}`
## Command Return
Each command returns something - there is no silent command.
The return is always in JSON format.
Examples:
`[0, null]` No error, no content
`[0, “Lorem Ipsum”]` No error, str as payload
`[0, {“Lorem”:1, “Ipsum”:2}]` No error, dict as payload
`[-900, “Unknown command”]` Error with description
# Commands by Functions
* [Gadget](Gadget) * [Gateway](Gateway)
