Serial Interface Manual
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TLS2 Monitoring Systems
Part No. 577013-767, Revision H
3
5.0
COMMAND MESSAGE FORMAT
All command and response messages are configured in a format which includes a surrounding envelope
of control characters and a function code and data field message. The control characters are described in
this section, while the function codes and data field messages are described in subsequent sections.
The system responds to a command message that has the following configuration:
SOH
Security Code
Function Code
Data Field
SOH is a fixed Control-A character (ASCII 01), and it indicates the beginning of the message.
The RS-232 security code is an optional six-digit code used to limit external serial access to the system
for security purposes. It can be set to any unique set of six characters, using either the front panel setup
menus or the external communication interface setup commands. The system will not respond to a
command without the proper security code.
The function code is a six character command code which the system interprets to determine the type of
action to take and response to return. System function codes and response messages are defined in
subsequent sections.
The data field is optional and contains information necessary to perform the selected function (such as
setup information).
If the system receives a command message string containing a function code that it does not recognize, it
will respond with a <SOH>9999FF1B<ETX>. The "9999" indicates that the system has not understood
the command, while the "FF1B" is the appropriate checksum for the preceding <SOH>9999 string.
There is one command which does not follow the above format. The escape command is performed by
sending an ESC (escape character, ASCII 27), to the system. It can be used to halt a response message at
any time before its completion.
