Digi Edgeport/1, Руководство по установке

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Edgeport configuration utility Port Flag Configuration tab
Edgeport USB Expansion Modules Installation Guide 18
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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.
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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.
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Fast Writes :
When an application sends a write to the driver, by default the Edgeport driver will wait
until all data has been transmitted out of the Edgeport 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 Edgeport device.
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Fast Reads :
This flag is used when an application requires that a read complete immediately. In the
read immediate case, the Edgeport driver will send a request to the Edgeport 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 Edgeport device for
additional data.
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Disable Plug & Play :
Uncheck this to allow Windows to detect Plug and Play serial devices, such as most modems.
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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received for ~200ms (receiver is no longer active).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 Edgeport 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.
The problem is that the Edgeport buffers the RX bytes and we poll the driver. If we do
not receive any bytes in 200ms we may report an erroneous event even if there are
available bytes in the Edgeport device or driver.