User Manual

Fast Flush (only flush local buffer)
1. We have added one optional Fast Flush function to Moxa new
NPort Real COM driver.
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 (about 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.
3. 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.
4. By default, the optional “Fast Flush” function is disabled. If you
would like to enable this function, double click on 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().”