User`s manual

NPort S8000 Series Software Installation/Configuration
7-10
FIFO
If FIFO is Disabled, the NPort S8000 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
S8000 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 S8000. 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 S8000. 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 S8000 is not powered on or is
disconnected. Note 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 continues to query the NPort’s
firmware several times to make sure no data is queued in the NPort’s 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 S8000. 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 S8000 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.
3. The Serial Parameters window in the following figure shows the default settings when the NPort S8000 is
powered on. However, the program can redefine the serial parameters to different values after the program
opens the port via Win 32 API.