User`s manual

NPort 6000 Series User’s Manual Software Installation/Configuration
10-10
Tx Mode
Hi-Performance is the default for Tx mode. After the driver sends data to the NPort 6000,
the driver immediately issues a “Tx Empty” response to the program. Under Classical mode,
the driver will not send the “Tx Empty” response until after confirmation is received from the
NPort 6000’s serial port. This causes lower throughput. Classical mode is recommended if
you want to ensure that all data is sent out before further processing.
FIFO
If FIFO is Disabled, the NPort 6000 will transmit 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.
Network Timeout
You can use this option to prevent blocking if the target NPort is unavailable.
Auto Network Re-Connection
With this option enabled, the driver will repeatedly attempt to re-establish the TCP connection
if the NPort 6000 does not respond to background “check alive” packets.
Return error if network is unavailable
If this option is disabled, the driver will not return any error even when a connection cannot
be established to the NPort 6000. With this option enabled, calling the Win32 Comm function
will result in the error return code “STATUS_NETWORK_UNREACHABLE” when a
connection cannot be established to the NPort 6000. This usually means that your host’s
network connection is down, perhaps due to a cable being disconnected. However, if you can
reach other network devices, it may be that the NPort 6000 is not powered on or is
disconnected. Not that Auto Network Re-Connection must be enabled in order to use this
function.
Fast Flush (only flushes the local buffer)
For some applications, the user’s program will use the Win32 “PurgeComm()” function
before it reads or writes data. After a program uses this PurgeComm() function, the NPort
driver continue to query NPort’s firmware several times to make sure no data is queued in the
NPort firmware buffer, rather than just flushing the local buffer. This design is used to satisfy
some special considerations. However, it may take more time (about several hundred
milliseconds) than a native COM1 due to the additional time spent communicating across the
Ethernet. This is why PurgeComm() works significantly faster with native COM ports on the
PC than with mapped COM ports on the NPort 6000. In order to accommodate other
applications that require a faster response time, the new NPort driver implements a new Fast
Flush option. By default, this function is enabled.
If you have disabled Fast Flush and find that COM ports mapped to the NPort 6000 perform
markedly slower than when using a native COM port, try to verify if “PurgeComm()”
functions are used in your application. If so, try enabling the Fast Flush function and see if
there is a significant improvement in performance.