> For the complete documentation index, see [llms.txt](https://help.boomerang3.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.boomerang3.com/s2-radio-system-manual/s2-system-description/s2-node/s2-communication-protocol/frame.md).

# Frame

The frame has one or two parts depending on command name header and data. 

Nodes discard frames longer then 64 bytes.

 There are UART commands and Radio commands. The UART commands do not result in any radio communication and are handled inside the PC node only. The Radio commands cause radio transmission and the answer from PC node depends on the radio communication result.

Example of UART command frame

| 1      | 2       | 3       | 4   | 5  | 6   | 7    | 8    | 9   |
| ------ | ------- | ------- | --- | -- | --- | ---- | ---- | --- |
| Length | ID Info | Command | GRP | ID | CRC | Data | Data | CRC |
| 09     | 00      | 10      | 01  | 01 | CRC | GRP  | ID   | CRC |

 

Example of Radio command frame

| 1      | 2       | 3       | 4   | 5  | 6     | 7   | 8      | 9      | 10  |
| ------ | ------- | ------- | --- | -- | ----- | --- | ------ | ------ | --- |
| Length | ID Info | Command | GRP | ID | To ID | CRC | Data   | Data   | CRC |
| 0A     | 11      | 35      | 01  | 01 | 02    | CRC | CAL\_V | CAL\_V | CRC |

### 1.1      Header


---

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