User Guide

FS-8704-11 Telnet Driver Manual Page 3 of 6
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3. Optional Configuration Items
3.1. Autoconnect Port
If a port is specified in the autoconnect port field, the first Telnet session to connect to the
FieldServer will immediately be connected to the specified port (see Using Serial Port
Capture below). Any further simultaneous Telnet sessions will see the usual command
prompt.
3.2. Autoconnect Mode
Two modes, Text and Binary, are available for use with Autoconnect Ports. Text mode is
optimized for manual use when using Telnet to communicate with a serial device that
presents a user interface (such as a text driven menu screen). This allows the user to
customize how tabs and linefeeds are sent and received. Also, the user can quit a port
capture by hitting Ctrl-C.
If the intention is to run a binary serial protocol over a Telnet connection, the Binary mode
must be specified. This does not modify the data stream in any way.
3.3. Login
If desired, a username and password can be set in the csv file to restrict access to all
functions modifying the operation of the Telnet driver, e.g. port, linefeed, tab. The Login
command will prompt the user for the username and password before these commands may
be used.
3.4. Timeout
A timeout can be set to close the Telnet session and its TCP connection after the specified
period of inactivity. Specify the timeout in seconds in the session_timeout field.
It is important to specify the session_timeout if the FieldServer is mainly used as a serial
protocol client continually communicating with the device. Under these circumstances, if a
Telnet session captures the serial port, the protocol driver is put on hold until the port is
released. If the user forgets to release the port and leaves the Telnet session connected, the
protocol driver on the FieldServer can never resume communications with the device, and
the bridge data is never updated. If the session_timeout is set, then a period of inactivity will
cause the port to be released and the Telnet session to be closed, so that the protocol driver
can resume its communication activity.