> For the complete documentation index, see [llms.txt](https://doc.open-tx.org/opentx-2-3-lua-reference-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.open-tx.org/opentx-2-3-lua-reference-guide/part_iii_-_opentx_lua_api_reference/general-functions-less-than-greater-than-luadoc-begin-general/serialread.md).

# serialRead(\[num])

@param num (optional): maximum number of bytes to read. If non-zero, serialRead will read up to num characters from the buffer. If 0 or left out, serialRead will read up to and including the first newline character or the end of the buffer. Note that the returned string may not end in a newline if this character is not present in the buffer.

Reads characters from the serial port. The string is allowed to contain any character, including 0.

@status current Introduced in 2.3.8

## Parameters

none

## Return value

* `str` string. Empty if no new characters were available.