Moxa Technologies NPort 5600 - Manual (Page 91)

NPort 5600 Series User’s Manual IP Serial LIB
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Fast Flush (only flush local buffer)
We have added one optional Fast Flush function to Moxa’s new NPort Real COM driver.
NPort Administrator Suite for 2G NPort adds it after version 1.2.
For some applications, the user’s program will use the Win32 “PurgeComm()” function
before it reads or writes data. With our design, after the program uses this Purge Comm()
function, the NPort driver will keep querying NPort’s firmware several times to make sure
there is really no data queued in the NPort firmware buffer, rather than just flushing the local
buffer. This kind of design is used because of some special considerations. However, it might
take more time (on the order of several hundred milliseconds) than a native COM1, because it
needs to work via Ethernet. That’s why the native COM ports on the motherboard can work
fast with this function call, but NPort requires much more time. In order to accommodate
other applications that require a faster response time, the new NPort driver implements a new
“Fast Flush” option. Note that by default, this function is disabled.
To begin with, make sure there are some “PurgeComm()” functions being used in your
application program. In this kind of situation, you might find that your NPort exhibits a much
poorer operation performance than when using the native COM1 port. Once you have enabled
the “Fast Flush” function, you can check to see if there has been an improvement in
performance.
By default, the optional “Fast Flush” function is disabled. If you would like to enable this
function, from the “NPort Administrator,” double click the COM ports that are mapped to the
NPort, and then select the “Fast Flush” checkbox. You should find that when “Fast Flush” is
enabled, the NPort driver will work faster with “PurgeComm().”
The Serial Parameter settings shown here are the default settings when the NPort is powered
on. However, the program can redefine the serial parameters to different values after the
program opens the port via Win 32 API.