SENA LS110 - Manual (Page 27)

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4.1.2 TCP Server Mode Operations
The LS110 in this mode acts as a TCP server, and the default TCP state is [Listen] in this mode. The
LS110 supports only one TCP socket connection per one serial port. If a connection is currently
established, any additional connection requests will be rejected. The remote host will be either
Ethernet-Serial communication devices acting as a TCP client or a socket program acting as a TCP
client running on users’ PC.
1) Typical State Transition
[Listen] --> [Sync-Received] --> [Established] --> [Data] --> [Closed] --> [Listen]
At start-up, an initial TCP state is [Listen]. If there is any incoming TCP connection request, the state
will be changed into [Sync-Received], then [Established], which means a session is opened. For a
while, data will be transferred between the hosts. This is the [Data] state. The session will be
disconnected due to the request of one of them, which is [Closed] state. And then, the state is
automatically changed to its original state, [Listen].
2) Operations
 Serial data transfer
When a session has been established, the LS110 reads the data from the serial port buffer till
internal serial buffer is full or inter-character time interval reaches the time specified as inter-
character timeout value. Then, it transfers the data to the IP address (or domain name) of the
remote host (See 4.3 Options for more details on inter-character timeout). If there’s no remote
host connected to the LS110, all the incoming data from the serial port are discarded.
 Session disconnection
The connected session will be disconnected when the remote host sends disconnection request
or when no data transfer activity is found through the serial port for a certain amount of time,
which is “Inactivity timeout” (See 4.3 Options for details on Inactivity timeout).
 IP Filtering
LS110 offers ‘IP Filtering’ (See 4.3.4 IP Filtering for details).