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# RxFreeSpaceAvailable

Notifies your driver that buffer space is available for your device’s data.

```
virtual void RxFreeSpaceAvailable();
```

## Discussion

Override this method and use it to read data asynchronously from the device’s serial port. When you finish reading the data, call the [`RxDataAvailable`](/documentation/SerialDriverKit/IOUserSerial/RxDataAvailable) method to let the system know the data is ready.

---

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