Serial Ports Monitor ActiveX Control supports the following standard IOCTL requests:

FunctionBrief Description
IOCTL_SERIAL_CLEAR_STATS This request clears the performance statistics for a serial device
IOCTL_SERIAL_CLR_DTR This request clears the data terminal ready control signal (DTR)
IOCTL_SERIAL_CLR_RTS  This request clears the request to send control signal (RTS)
 IOCTL_SERIAL_CONFIG_SIZE This request returns information about configuration size
 IOCTL_SERIAL_GET_BAUD_RATE This request returns the baud rate that is currently set for a serial device
IOCTL_SERIAL_GET_CHARS This request returns the special characters that Serial Port uses with handshake flow control
IOCTL_SERIAL_GET_COMMSTATUS This request returns information about the communication status of a serial device
IOCTL_SERIAL_GET_DTRRTS This request returns information about the data terminal ready control signal (DTR) and the request to send control signal (RTS)
IOCTL_SERIAL_GET_HANDFLOW This request returns information about the configuration of the handshake flow control set for a serial device
IOCTL_SERIAL_GET_LINE_CONTROL This request returns information about the line control set for a serial device. The line control parameters include the number of stop bits, data bits, and the parity
IOCTL_SERIAL_GET_MODEM_CONTROL This request returns the value of the modem control register
IOCTL_SERIAL_GET_MODEMSTATUS This request updates the modem status, and returns the value of the modem status register before the update
IOCTL_SERIAL_GET_PROPERTIES This request returns information about the capabilities of a serial device
IOCTL_SERIAL_GET_STATS This request returns information about the performance of a serial device. The statistics includes the number of characters transmitted and received, and useful error statistics. The driver continuously increments performance values.
IOCTL_SERIAL_GET_TIMEOUTS This request returns the timeouts values that Serial driver uses with read and write requests
IOCTL_SERIAL_GET_WAIT_MASK This request returns the event wait mask that is currently set on a serial device
IOCTL_SERIAL_IMMEDIATE_CHAR This request causes a specified character to be transmitted as soon as possible. The immediate character request completes immediately after any other write that might be in progress. Only one immediate character request can be pending at a time
IOCTL_SERIAL_LSRMST_INSERT This request enables or disables the insertion of information about line status and modem status in the receive data stream
IOCTL_SERIAL_PURGE This request cancels the specified requests and deletes data from the specified buffers
IOCTL_SERIAL_RESET_DEVICE This request resets a serial device
IOCTL_SERIAL_SET_BAUD_RATEThis request sets the baud rate on a serial device
IOCTL_SERIAL_SET_BREAK_OFF This request sets the line control break signal inactive 
IOCTL_SERIAL_SET_BREAK_ON This request sets the line control break signal active
IOCTL_SERIAL_SET_CHARS This request sets the special characters that Serial Port uses for handshake flow control
IOCTL_SERIAL_SET_DTR This request sets DTR (data terminal ready)
IOCTL_SERIAL_SET_FIFO_CONTROLThis request sets the FIFO control register (FCR) 
IOCTL_SERIAL_SET_HANDFLOW This request sets the configuration of handshake flow control
IOCTL_SERIAL_SET_LINE_CONTROLThis request sets the line control register (LCR). The line control register controls the data size, the number of stop bits, and the parity 
 IOCTL_SERIAL_SET_MODEM_CONTROL This request sets the modem control register
IOCTL_SERIAL_SET_QUEUE_SIZE This sets the size of the internal receive buffer. If the requested size is greater than the current receive buffer size, a new receive buffer is created. Otherwise, the receive buffer is not changed
IOCTL_SERIAL_SET_RTS This request sets RTS (request to send)
IOCTL_SERIAL_SET_TIMEOUTS This request sets the time-out values that the driver uses with read and write requests 
IOCTL_SERIAL_SET_WAIT_MASK This request configures Serial to notify a client after the occurrence of any one of a specified set of wait events
IOCTL_SERIAL_SET_XOFF This request emulates the reception of an XOFF character. The request stops reception of data 
IOCTL_SERIAL_SET_XON This request emulates the reception of a XON character, which restarts reception of data
IOCTL_SERIAL_WAIT_ON_MASK This request is used to wait for the occurrence of any wait event specified by using an IOCTL_SERIAL_SET_WAIT_MASK request
IOCTL_SERIAL_XOFF_COUNTER This request sets an XOFF counter. An XOFF counter request supports clients that use software to emulate hardware handshake flow control