Serial Port Monitor ActiveX Control provides a set of events to notify about the changes in state and data being sent/received via the port which is monitored by the ActiveX Control:

EventBrief Description
OnBaudRate The baud rate change was detected
OnCTS The CTS (clear-to-send) signal changed state
 OnDCD The RLSD (receive-line-signal-detect) signal changed state
OnDSR The DSR (data-set-ready) signal changed state
 OnDTR The DTR (data-terminal-ready) signal changing state
 OnHandFlow The flow control change detected
 OnLineControl The line control change detected
OnOpenClose The port Open or Close operation detected
OnRead Data is being read from the port (VARIANT analog of OnReadData)
 OnRing A ring indicator was detected
OnRTS RTS (ready-to-send) signal changing state
OnWrite Data is being written into port (VARIANT analog of OnWriteData)
OnWriteData Data is being written into port
OnReadData Data is being read from port
 OnIrp Provides low-level access to device driver
 OnTimeouts Timeouts update on either serial port is detected

See also

Serial Port Monitor Methods OverviewSerial Port Monitor Properties Overview