# serial.read

## Function

Read data from the opened serial port. This method retains historical compatibility behavior: a String is returned when valid UTF-8 is read, otherwise a byte array is returned.

## Syntax

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

## Parameters

No parameters.

## Return value

| Type | Description |
| ------ | ------ |
| String/Array | Returns String when legal UTF-8 is read; otherwise returns byte array. |

## Example

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

// Output: String
echo(type(result))
```

## Notes

- Throws an underlying device error when the read fails.
- The new binary protocol uses `read_bytes()` first to avoid the return type changing with the content.