ICS ELECTRONICS 9099, Instruction Manual

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The Raw Socket service has limited resources and therefore has a fixed 120
second inactivity timeout. This means that if the client fails to send anything for
a period of 120 seconds, the service will automatically close the socket which
prevents further communication. This timeout can be reset by the sending of
any data, for example sending of a CR (0x0D) will reset the timer with the CR
being discarded by the service.
If you are connecting to the service and having periods of inactivity (such as
editing of scripts or ending individual characters with long pauses) between
actions, then this will result in loss of connectivity. The better way is to have
the script perform a socket connection, perform the required actions and then
disconnect the socket connection.
Raw Sockets default to No Echo, but Echo can be turned on by sending a ^E
(0x05) or enabling Echo on the HTML Configuration Page with a browser..
This will result in each character being returned to the client as it is received.
Default behavior is to not echo received data which means you will not see
what you are typing when you manually telnet to the device. Other control
characters are defined in the Raw Socket documentation.
Important to note is that the Raw Socket data must be terminated by a LF
(0x0A). Sending data terminated by a CR will not be acted upon since a CR
is simply discarded by the 9099's Raw Socket service. Therefore when us-
ing telnet you must type the command and then terminate it with a LF (use a
CTRL-J) for the service to execute the typed command. Raw Socket clients
like Hyperterminal must be configured to send a new line (linefeed) when
pressing the Enter key.
Using scripting with Raw Sockets is not recommended. While scripting does
send messages to the 9099, it often closes the socket immediately after send-
ing the message which blocks any replies and part of an echoed message (if
echo is enabled).
While using Raw Sockets (telnet) seems very simple, it must be understood
that the ICS devices have very firm rules on usage. Most of these rules are as
a result of the small amount of resources available for any embedded device.
Limitations such as a maximum of 4 connections at a time, the 120 second
inactivity timer and other such rules are in an attempt to maximize the func-
tionality of the device while dealing with the limited resources of the embedded
device. Please study the documentation regarding Raw Sockets before actually
designing your application or using the device.