Serial Ports ActiveX Control provides a set of events to control serial port state changes:
| Event | Brief Description |
| OnRxChar | A character was received and placed in the input buffer |
| OnCTS | The CTS (clear-to-send) signal changed state. |
| OnDSR | The DSR (data-set-ready) signal changed state. |
| OnRing | A RING signal changed state. |
| OnBreak | A break was detected on input. |
| OnDCD | The DCD signal changed state. |
| OnTxEmpty | The last character in the output buffer was sent. |
| OnRxFlag | The event character was received and placed in the input buffer. |
| OnCommEvent | An event of the first or second provider-specific type occurred. |
| OnCommError | A line-status error occurred. Line-status errors are CE_FRAME, CE_OVERRUN, and CE_RXPARITY. |
| OnLatencyExpiry | No data was received during the period, set by SetLatencyExpiry method. |
| OnPortAdded | A new serial port was added to the system. |
| OnPortRemoved | A serial port was removed from the system. |
| OnChangePortsList | The list of serial ports was changed. |
See also