# serial.read_bytes

## Function

Read raw bytes from the open serial port and return Bytes.

## Syntax

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

## Parameters

No parameters.

## Return value

| Type | Description |
|------|------|
| Bytes | The raw bytes currently read; empty Bytes is returned when there is no data. |

## Code Example

```bt
port = device.open({type: 'serial', port: 'COM3'})
data = port.read_bytes()

// Output: Bytes
print type(data)
```

## Notes

- Serial port reading is controlled by `device.open({timeout: ...})`.
- Return value length is limited by `BT_BYTES_LIMIT`.