SENA Rhio10 - Manual (Page 27)

27
there’s no connection close request. Although inactivity timeout is disabled, the Rhio10 will
check the connection status between the Rhio10 and the remote host by sending “keep alive”
packets periodically. If the remote host does not answer the packets, it is regarded that the
connection is down unintentionally. Then, the Rhio10 will force to close the existing TCP
connection.
3.2.2 TCP Client Mode Operation
The RHIO10 works as a TCP client, and the default TCP state is [Closed] in this mode. The
remote host will be 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 changed in I/O state, the Rhio10 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,
I/O state 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
I/O state data transfer
Whenever there is any change in the I/O status, it tries to connect to the user-defined IP
address of the remote host, if TCP session is not established yet. If the RHIO10 succeeds in
connecting to the remote host, the I/O status data will be transferred to the host. Otherwise, I/O
status data will be cleared.
Session disconnection
The connected session will be disconnected when the remote host sends disconnection request
or when no I/O data transfer activity is found for certain amount of time, which is “Inactivity
timeout”.
Connection request from remote host
All the incoming TCP connection requests will be rejected in TCP client mode.