# device.open

## Function

Open the device connection. The current implementation supports serial serial devices.

## Syntax

```bt
device.open(config)
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| config | Object | Yes | None | The device configuration object. |

## Serial port configuration field

Currently `device.open(config)` only supports opening serial serial devices. `config` fields are as follows:

| Field | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| type | String | No | `serial` | Device type. Currently only `serial` is supported, passing in other values will throw an unsupported device type error. |
| port | String | Yes | None | System serial port name, such as `COM3`, `/dev/ttyUSB0`. Usually comes from the `device.scan()` return object's `port` fields. |
| baud_rate | Int | No | `9600` | Baud rate, indicating the number of symbols transmitted per second. Must be consistent with the external device configuration. |
| data_bits | Int | No | `8` | Number of data bits. Supports `5`, `6`, `7`, `8`. |
| stop_bits | Int | No | `1` | Number of stop bits. Supports `1`, `2`. |
| parity | String | No | `none` | Parity digit. Supports `none`, `odd`, `even`; empty strings are processed as `none`. |
| timeout | Int | No | `1000` | Read and write timeout, in milliseconds. |

## Return value

| Type | Description |
| ------ | ------ |
| Device | Returns the opened device handle. |

## Example

```bt
// Replace port with the actual serial port name returned by device.scan().
serial = device.open({
    type: 'serial',
    port: 'COM3',
    baud_rate: 9600,
    data_bits: 8,
    stop_bits: 1,
    parity: 'none',
    timeout: 1000
})

result = type(serial)

// Output: Device
print result
```

## Notes

-Configuration fields use snake_case uniformly.
- `baud_rate`, `data_bits`, `stop_bits`, `parity` must be consistent with the serial port parameters of the hardware device, otherwise normal communication may not be possible.