15.25
Date Code 20171006 Instruction Manual SEL-400 Series Relays
Communications Interfaces
SEL Protocol
Most commands are available only in SEL ASCII format. Selected commands
have versions in both standard SEL ASCII and Compressed ASCII formats.
Compressed ASCII reports generally have fewer characters than conventional
SEL ASCII reports, because the compressed reports reduce blanks, tabs, and
other white space between data fields to a single comma.
Compressed ASCII Message Format
Each message begins with the start-of-transmission character, STX, and ends
with the end-of-transmission character, ETX:
<STX><MESSAGE LINE 1><CR><LF>
<MESSAGE LINE 2><CR><LF>
...
<LAST MESSAGE LINE><CR><LF><ETX>
Each line in the message consists of one or more data fields, a checksum field,
and a CRLF. Commas separate adjacent fields. Each field is either a number or a
string. Number fields contain base-10 numbers using the ASCII characters 0–9,
plus (+), minus (-), and period (.). String fields begin and end with quote marks
and contain standard ASCII characters. Hexadecimal numbers are contained in
string fields.
The checksum consists of four ASCII characters that are the hexadecimal repre-
sentation of the two-byte binary checksum. The checksum value is the sum of the
first byte on a line (first byte following
<STX>, <CR>, or <CR><LF>) through the
comma preceding the checksum.
If you request data with a Compressed ASCII command and these data are not
available, (in the case of an empty history buffer or invalid event request), the
relay responds with the following Compressed ASCII format message:
<STX>“No Data Available”,“0668”<CR><ETX>
Table 15.18 lists the typical Compressed ASCII commands and contents of the
command responses. The Compressed ASCII commands are described in
Section 14: ASCII Command Reference.
where:
No Data Available
is a text string field.
0668
is the checksum field, which is a hexadecimal
number represented by a character string.
Table 15.18 Typical Compressed ASCII Commands (Sheet 1 of 2)
Command Response Access Level
BNAME ASCII names of Fast Meter status bits 0
CASCII Configuration data of all Compressed ASCII commands
available at access levels > 0
0
CBREAKER Circuit breaker data 1
CEVENT Event report 1
CHISTORY List of events 1
CPR Displays the first 20 rows of the profile report, with the
oldest row at the bottom and the latest row at the top
CSER Sequential Events Recorder report 1
CSTATUS Self-diagnostic status 1
CSUMMARY Summary of an event report 1
DNAME ASCII names of digital I/O reported in Fast Meter 0
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