---
title: "system.serial.port"
description: "Returns a context manager wrapping a serial port, allowing the rest of the system to interact with that port."
---

# system.serial.port

> Returns a context manager wrapping a serial port, allowing the rest of the system to interact with that port.

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

## Description
Returns a [context manager](https://docs.python.org/2.7/reference/datamodel.html#with-statement-context-managers) wrapping a serial port, allowing the rest of the system to interact with that port. This function effectively combines the [system.serial.configureSerialPort](system-serial-configureSerialPort.md), [system.serial.openSerialPort](system-serial-openSerialPort.md), and [system.serial.closeSerialPort](system-serial-closeSerialPort.md) functions into a single call. 

Intended to be used with the [Python 'with' statement](https://docs.python.org/2.7/reference/compound_stmts.html?highlight=statement#the-with-statement). The object aliased in the 'with' statement has special access to all of the other [system.serial](system-serial.md) functions, allowing for reads and writes.

Closing the port happens automatically once the 'with' statement ends. 

Accepts the same arguments as [configureSerialPort](system-serial-configureSerialPort.md), and access to constants must be prefixed by "system.serial." (as shown in the parameter descriptions). 

## 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.port(port, [bitRate], [dataBits], [handshake], [hardwareFlowControl], [parity], [stopBits])`

### Parameters
Type | Parameter | Description 
------- | ------- | ------
String  | `port` | The name of the serial port, e.g., "COM1" or "/dev/ttyS0". This parameter is required.
Integer |  `bitRate` | Configure the bit rate. Valid values are defined by the following constants [optional]:  `system.serial.BIT_RATE_110, system.serial.BIT_RATE_150`, `system.serial.BIT_RATE_300, system.serial.BIT_RATE_600`, `system.serial.BIT_RATE_1200, system.serial.BIT_RATE_2400`, `system.serial.BIT_RATE_4800, system.serial.BIT_RATE_9600`, `system.serial.BIT_RATE_19200, system.serial.BIT_RATE_38400`, `system.serial.BIT_RATE_57600, system.serial.BIT_RATE_115200`, `system.serial.BIT_RATE_230400, system.serial.BIT_RATE_460800`, `system.serial.BIT_RATE_921600`
Integer |  `dataBits` | Configure the data bits. Valid values are defined by the following constants [optional]: `system.serial.DATA_BITS_5, system.serial.DATA_BITS_6`, `system.serial.DATA_BITS_7, system.serial.DATA_BITS_8`
Boolean |  `hardwareFlowControl` | Configure hardware flow control. On or off. [optional]
Integer |  `parity` |  Configure parity. Valid values are defined by the following constants [optional]:`system.serial.PARITY_EVEN, system.serial.PARITY_ODD`, `system.serial.PARITY_MARK, system.serial.PARITY_SPACE, system.serial.PARITY_NONE`
Integer |  `stopBits` | Configure stop bits.Valid values are defined by the following constants [optional]:`system.serial.STOP_BITS_1, system.serial.STOP_BITS_2`

:::note
The serial library was updated in 8.0. Any constants, like HANDSHAKE, that do not have an equivalent value will result in a value of 0.
:::

### Returns
**PortManager** - A wrapper around the configured port, that can be entered by using a 'with' statement. The port will automatically close on exiting the 'with' statement scope.

### Scope
Gateway, Vision Client, Perspective Session

## Using the PortManager
The PortManager is the primary way to interact with a serial port when using this function. It has special access to the other system serial functions. Specifically:

* [system.serial.readBytes](system-serial-readBytes.md)
* [system.serial.readBytesAsString](system-serial-readBytesAsString.md)
* [system.serial.readLine](system-serial-readLine.md)
* [system.serial.readUntil](system-serial-readUntil.md)
* [system.serial.sendBreak](system-serial-sendBreak.md)
* [system.serial.write](system-serial-write.md)
* [system.serial.writeBytes](system-serial-writeBytes.md)

Calling these functions from the PortManager does **not** require the 'port' parameter, as the port is implied by system.serial.port. However all other parameters are available (see the linked pages in the bullet list above).

In addition, you do not include 'system.serial.' when accessing the other serial functions mentioned above, as the aliased object has access to them. Thus:

```
# Correct
with system.serial.port("COM1") as port:
    port.write("some string")
 
# Incorrect
with system.serial.port("COM1") as port:
    system.serial.write("COM1", "some string")
```

## Code Examples

```python title="Example 1: Simple Example with Descriptions"
# Reads a value from a port.
 
# First we call the function using a 'with' statement, and create an aliased object named 'port'
with system.serial.port("COM1", bitRate=system.serial.BIT_RATE_9600) as port:
 
    # Within the 'with' statement, we can call other serial functions by referencing the aliased object.
    # Meaning, in this example, 'port' can easily call the system.serial.readLine() function with the following:
    line = port.readLine(60000)
```

```python title="Example 2: Using all Parameters"
# Same idea as example one, but uses all available parameters.
with system.serial.port(
        port = "COM1",
        bitRate = system.serial.BIT_RATE_110,
        dataBits = system.serial.DATA_BITS_5,
        handshake = system.serial.HANDSHAKE_CTS_DTR,
        hardwareFlowControl = False,
        parity = system.serial.PARITY_EVEN,
        stopBits = system.serial.STOP_BITS_1) as port:
     
    line = port.readLine(60000)
```