SENA NEMO10-SK - Manual (Page 36)

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4.2 TCP Client Mode Operations
4.2.1 Overview
The NEMO10 works as a TCP client, and the default TCP state is [Closed] in this mode. The remote
host will be either Ethernet-Serial communication devices acting as a TCP server or a socket program
acting as a TCP server running on users’ PC.
1) Typical State Transition
[Closed] --> [Sync-Sent] --> [Established] --> [Data] --> [Closed]
At start-up, an initial TCP state is [Closed]. If there is any incoming data through the serial port, the
NEMO10 will try to connect to a user-defined remote host. Then, the state will be changed to [Sync-
Sent], which means the connection request is being sent. If the remote host accepts the request, the
state will be changed into [Established], which means a session has been opened. For a while, data
will be transferred between the hosts. This is [Data] state. The session will be disconnected due to the
request of one of them, which is its original state, [Closed].
2) Operations
 Serial data transfer
Whenever the serial device sends data through the serial port of the NEMO10, data will be
accumulated to the serial port buffer of the NEMO10. If the internal serial port buffer is full or inter-
character time interval reaches to the time specified as inter-character timeout value, it tries to
connect to the user-defined IP address of the remote host, if TCP session is not established yet. If
the NEMO10 succeeds in connecting to the remote host, the data in the serial port buffer will be
transferred to the host. Otherwise, all the data stored in the buffer will be cleared.
 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 certain amount of time, which
is “Inactivity timeout”. All the data remained in the serial port buffer will be cleared when it is
disconnected.
 Connection request from remote host
All the incoming TCP connection requests will be rejected in TCP client mode.