SENA SS800 - Manual (Page 49)

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 Max. allowed connection
The Super Series supports multiple connections from external host(s) to a serial port up to 32. But if
there are remote host connections by the remote host list configuration already, possible number of
connection is reduced to (Max. allowed connection - remote host(s) connected already). For example,
if user set Max. allowed connection as 32 and if there are 3 connections from Super Series to remote
hosts, which are configured in the remote host list, then maximum number of connection from external
hosts to a serial port will be reduced to 29 (=32 – 3). For more detail information for remote host list
configuration, please refer to 4.2.5. Remote Host Configuration section.
 Cyclic Connection
If Cyclic Connection function is enabled, the Super Series will make an attempt to connect to the user-
defined remote host(s) at a given interval even if there’s no incoming serial data from the device
connected to that serial port. If there is data on the remote host(s) to be sent to serial device, it can be
transferred to the serial device via Super Series’s serial port after the connection is established.
Eventually, users can monitor the serial device periodically by making the remote host send the serial
command to the Super Series whenever it is connected to the remote host. This option is useful when
users need to gather the device information periodically even if the serial device does not send its data
periodically. Figure 4-6 shows the State Transition Diagram of the session operations in TCP mode.
 Inactivity Timeout
When Inactivity Timeout function is enabled, connection between remote host(s) and Super Series will
be closed automatically if there is no data transmission during the value which is set in Inactivity
Timeout configuration.
 Socket ID
When Super Series connects remote host(s), sometimes it is needed to identify the device using the
string. In this case, if user specifies specific strings in Socket ID, Super Series send these strings first
before start the data transmission. User can specifies either Serial Numebr or specific strings up to 49
characters as Socket ID.(This option can be changed only by root user) In TCP mode, specified
Socket ID strings are sent once at the time of establishing TCP connection.
 TCP Nagle algorithm
Modern TCP implementations include a mechanism, known as the Nagle algorithm, which prevents
the unnecessary transmission of a large number of small packets. This algorithm has proved useful in
protecting the Internet against excessive packet loads. However, some applications suffer
performance problems as a result of the traditional implementation of the Nagle algorithm.(An
interaction between the Nagle algorithm and TCP's delayed acknowledgement policy can create
especially severe problems, through a temporary “deadlock.”) TCP Nagle algorithm can be disabled or