Moxa Technologies NPort 5200 Series User Manual page 65

Fast Flush (only flush local buffer)
1. We have added one optional Fast Flush function to Moxa new NPort Real COM driver.
NPort Administrator Suite for 2G NPort adds it after version 1.2.
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, from the "NPort Administrator," 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()."
The Serial Parameter settings shown here are the default settings when
the NPort 5200 is powered on. However, the program can redefine the
serial parameters to different values after the program opens the port via
Win 32 API.
After setting the COM Mapping,
remember to select Apply Change to
save the information in the host system
registry. The host computer will not have
the ability to use the COM port until after
Apply Change is selected.
Select Discard Change to tell
Administrator NOT to save the COM
Mapping information to the host.
Configuring Windows Administrator
NPort 5200 Series User's Manual 6-15