---
title: "system.serial.readBytes"
description: "Read numberOfBytes bytes from a serial port."
---

# system.serial.readBytes

> Read numberOfBytes bytes from a serial port.

This function is used in **Python Scripting**.

## Description
Read `numberOfBytes` bytes from a serial port.

## Client Permission Restrictions
This scripting function has no [Client Permission](projects\project-properties\project-properties.md#client---permissions) restrictions.

## Syntax
`system.serial.readBytes(port, numberOfBytes [, timeout])`

### Parameters

|Type|Parameter|Description|
|--|--|--|
|String |`port` | The previously configured serial port to use.|
|int |`numberOfBytes` | The number of bytes to read.|
|int |`timeout` | Maximum amount of time, in milliseconds, to block before returning. Default is 5000. [optional]|
### Returns
**byte[]** - A byte[] containing bytes read from the serial port.
### Scope
All