---
title: "system.serial.writeBytes"
description: "Write a List[Byte] to a serial port."
---

# system.serial.writeBytes

> Write a List[Byte] to a serial port.

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

## Description
## Client Permission Restrictions
This scripting function has no [Client Permission](../../../ignition-modules/vision/vision-project-properties/vision-project-properties.md#vision-permissions-properties) restrictions.

## Syntax
`system.serial.writeBytes(port, toWrite)`

### Parameters
Type | Parameter | Description 
------- | ------- | ------
String| `port` | The previously configured serial port to use.
List[Byte]| `toWrite` | The List[Byte] to write.

### Returns
Nothing
### Scope
Gateway, Vision Client, Perspective Session

## Code Examples

```python title="Code Snippet"
# This example will write a list of bytes to a port called "COM1"
port = "COM1"
toWrite = [1,1,0,0,1]
 
system.serial.writeBytes(port,toWrite)
```