---
title: "system.serial.closeSerialPort"
description: "Closes a previously opened serial port."
---

# system.serial.closeSerialPort

> Closes a previously opened serial port.

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

## Description
Closes a previously opened serial port. Returns without doing anything if the named serial port is not currently open. Will throw an exception if the port is open and cannot be closed.

## 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.closeSerialPort(port)`

### Parameters
Type | Parameter | Description 
------- | ------- | ------
String | `port` | The name of the serial port, e.g., "COM1" or "dev/ttyS0".

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

## Code Examples

```python title="Code Snippet - Using a Literal Value"
# This example will close a port called "COM1".
system.serial.closeSerialPort("COM1")
```

```python title="Code Snippet - Using a Variable"
# This example will close a port using a variable called port that has a value of "COM1"
port = "COM1"
system.serial.closeSerialPort(port)
```