SENA PS400 - Manual (Page 47)

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Figure 4-22. Set up the cryptography method and cryptography key string
4.4 Options
4.4.1 Inactivity timeout
The purpose of this parameter is to maintain the TCP connection state as Closed or Listen in TCP
host modes or to close UDP virtual connection in UDP server mode unless there is any data transfer
between the serial device and the HelloDevice Pro Series. If there is no incoming or outgoing data
through the serial port during the specified inactivity timeout interval, the existing TCP connection or
virtual UDP connection will be closed automatically.
If the value of inactivity timeout is set to 0 and the host mode is set to one of the TCP modes, the
current TCP connection is maintained unless there’s no connection close request. Although inactivity
timeout is disabled, the HelloDevice Pro Series will check the connection status between the
HelloDevice Pro Series 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
HelloDevice Pro Series will force to close the existing TCP connection.
If the value of inactivity timeout is set to 0 and the host mode is set to UDP server mode, virtual UDP
connection with the first remote host that sends UDP packet to the HelloDevice Pro Series will be
maintained forever till device is rebooted.
Note:
At least, this value should be set larger than that of inter-character timeout. To prevent the unintended
loss of data due to the session disconnection, it is highly recommended that this value is set large
enough so that the intended data transfer is completed.
4.4.2 Inter-character timeout
This parameter defines the interval that the HelloDevice Pro Series fetches the overall serial data from
its internal buffer. If there is incoming data through the serial port, the HelloDevice Pro Series stores
data into the internal buffer. The HelloDevice Pro Series transfers data stored in the buffer via TCP/IP,
only if the internal buffer is full or if the inter-character time interval reaches to the time specified as
inter-character timeout.
Optimal inter-character timeout would be different according to your application but at least it must be
larger than one character interval within specified baud rate. For example, assume that the serial port
is set to 1200 bps, 8 Data bits, 1 stop bit, and no parity. In this case, the total number of bits to send a
character is 10 bits and the time required to transfer one character is