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NPort 5400 Series User’s Manual Configuring NPort Administrator
6-22
6. Select the COM No.
COM ports that are “In use” or “Assigned” will also be indicated in this drop-down list.
If you select multiple serial ports or multiple NPort 5400s, remember to check the “Auto
Enumerating” function to use the COM No. you select as the first COM No.
7. Hi-performance mode is the default for Tx mode. If the driver completes sending data out to
the NPort 5400, the driver will respond “Tx Empty” to the program.
Under classical mode, the driver will not notify the user’s program that Tx is completed until
all Tx data has been sent out from the NPort 5400. This mode will cause lower throughput. If
you want to ensure that all data is sent out before further processing, classical mode is
recommended.
Enable/Disable Tx/Rx FIFO. If disabled, NPort 5400 will send one byte each time the Tx
FIFO becomes empty; and an Rx interrupt will be generated for each incoming byte. This will
result in a faster response and lower throughput. If you want to use XON/XOFF flow control,
we recommend setting FIFO to Disable.
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.