Setting Read and Write Timeouts for a Serial Device
A client can use an IOCTL_SERIAL_SET_TIMEOUTS request to set time-out values that the system-supplied Serial.sys driver uses for read and write requests. Serial.sys continues to transfer bytes until the requested number of bytes are transferred or a time-out event occurs.
The time-out operation in Serial.sys is compliant with the user-mode operation of COM ports that is supported by the communication functions that are supported by the Windows Base Services in the Microsoft Windows SDK.
Note that the time-out operation is not applied to a pending request while it is queued. The time-out operation is applied to a request after the request becomes current (that is, Serial.sys starts to process the request).
For more information about the read and write time-outs, see the following:
The SERIAL_TIMEOUTS structure in the Ntddser.h header file in the Windows Driver Kit (WDK).