E5805A USB/RS232 Interface
When the Ignore Tx Purge flag is set the
SERIAL_PURGE_TXCLEAR command is ignored. The function does not purge the write buffer.
•Disable Plug & Play: (Windows 2k/XP only)
Do not let the serial port enumerator detect devices plugged into the 4 Port Interface.
•Timer Logic: (Windows 98SE only)
If the application uses PortSetReadCallBack(), the notification routine is only 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 triggers and calls 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routine if some amount of data is available in the RX buffer, but no new data has been received for ~200ms (receiver is no longer active).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 E5805A USB/RS232 Interface’s buffering. However, if you set the flag, the read is completed when ~200 ms of no activity is detected.
Here is a comment from the code:
If the receiver is active, then do not complete this read. The problem is that the device 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 device or driver.
Test Ports - Performs a confidence test on the internal workings of the serial ports..
10 | E5805A USB/RS232 Interface |
