Serial Ports Monitor ActiveX Control supports the following standard IOCTL requests:
| Function | Brief 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_RATE | This 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_CONTROL | This request sets the FIFO control register (FCR) |
| IOCTL_SERIAL_SET_HANDFLOW | This request sets the configuration of handshake flow control |
| IOCTL_SERIAL_SET_LINE_CONTROL | This 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 |