Date Code 20010518 Message Strings 8-1
SEL-2020 Instruction Manual
SECTION 8: MESSAGE STRINGS
INTRODUCTION
This section provides information about the characters, special sequences of characters, and pre-
defined strings that you can use in a number of SEL-2020 settings. At the end of this section and
also on a blue pull-out card at the end of the book is a summary list of special characters and pre-
defined strings.
OVERVIEW
A string is a sequence of characters that make up part, or all, of a message command or identifier
label. Each character may be an ASCII printable character or any 8-bit code that represents a
nonprintable character. You use these strings in the following ways:
• Device and Port IDs, termination strings, and modem startup strings in
Port configuration using the SET P command.
• Startup sequence for an IED and message strings in auto-messages using the SET A
command.
• User-defined commands and responses using the SET U command.
Note: You should avoid using LMD prefix characters in Master port user-defined commands.
For an explanation of LMD and a list of LMD prefix characters see Appendix C: LMD
Protocol.
Message strings consist of literal characters, special sequences, and pre-defined strings. Literal
characters include both ASCII printable and non-printable characters. Special sequences are
strings that are interpreted to have a special meaning when they are used, such as dial a particular
phone number, or output a specified set of database data. Pre-defined strings are used with SEL
IEDs to represent certain predefined operations, such as 20METER means collect meter data in
best method available for attached device. The following sections further describe these types of
message sequences.
LITERAL CHARACTERS
Message strings typically contain some literal characters. These consist of both ASCII printable
characters and non-printable characters. Printable characters (except ‘\’) are entered into a string
by directly entering the character (depressing the key for that character on your keyboard). You
can also enter any character based on its 8-bit code. To enter a non-printable character (or
special sequence strings) using printable characters, you must use a special sequence to indicate
that you are entering something other than a printable character. These sequences always begin
with a backslash (‘\’). Table 8.1 shows the format of the various special character sequences
available.
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