Black Box IC1000A User Manual page 7

CHAPTER 4: OPERATION
Ignore Flush
If an application sends IRP_MJ_FLUSH_BUFFERS, it will be ignored. The following is an excerpt from Microsoft
documentation:
Drivers of devices with internal caches for data and drivers that maintain internal buffers for data must handle this
request.
When Sent
Receipt of a flush request indicates that the driver should flush the device's cache or its internal buffer, or, possibly, should
discard the data in its internal buffer.
Operation
The driver transfers any data currently cached in the device or held in the driver's internal buffer(s) before completing the
flush request. The driver of an input-only device that buffers data internally might simply discard the currently buffered
device data before completing the flush IRP, depending on the nature of its device.
Fast Writes
When an application sends a write to the driver, by default the USB to RS-232 Converter driver will wait until all data has
been transmitted out of the USB to RS-232 Converter device before completing the write. When the Fast Writes flag is set,
we complete the write even if data is still buffered in the driver and the USB to RS-232 Converter device.
Fast Reads
This flag is used when an application requires that a read complete immediately. In the read immediate case, the USB to
RS-232 Converter driver will send a request to the USB to RS-232 Converter device asking for any buffered data to be sent
up. This buffered data will be included when the read completes. If this flag is set, the driver will not query the USB to
RS-232 Converter device for additional data.
Disable Plug & Play
Uncheck this to allow Windows to detect Plug and Play serial devices, such as most modems.
Timer Logic: (Windows 9x only)
If the application uses PortSetReadCallBack(), the notification routine will only be called when the number of bytes in the
receive buffer is greater then the RX trigger. The Microsoft serial VxD also implements a timer that will trigger and call the
notification routine if some amount of data is available in the RX buffer but no new data has been received for ~200ms
(receiver is no longer active).
We do not enable this behavior by default because of the nature of USB to RS-232 Converter buffering.
But if you set the flag we will complete the read when we detect ~200 ms no activity.
The code specifies that if the receiver is active, the read will not be completed.
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