Schweitzer Engineering Laboratories SEL-749M - SEL ASCII Protocol Details

7.6
SEL-749M Relay Instruction Manual Date Code 20080918
Communications
SEL ASCII Protocol Details
SEL Communications Protocols
SEL ASCII. This protocol is described in SEL ASCII Protocol Details on
page U.7.6.
SEL Compressed ASCII. This protocol provides compressed versions of
some of the ASCII commands. The compressed commands are
described in SEL ASCII Protocol Details on page U.7.6 and the
protocol is described in Appendix C: SEL Communications
Processors.
SEL Fast Meter. This protocol supports binary messages to transfer
metering and digital element messages. Compressed ASCII commands
that support Fast Meter are described in SEL ASCII Protocol Details
and the protocol is described in Appendix C: SEL Communications
Processors.
SEL Fast Operate . This protocol supports binary messages to transfer
operation messages. The protocol is described in Appendix C: SEL
Communications Processors.
Modbus RTU Protocol
The SEL-749M provides Modbus RTU support at Port 3 or Port 4, but not
concurrently. Modbus is described in Appendix D: Modbus RTU
Communications Protocol.
DeviceNet
The SEL-749M provides DeviceNet™ support. DeviceNet is an optional
protocol described in Appendix E: DeviceNet.
SEL ASCII Protocol Details
Message Format
SEL ASCII protocol is designed for manual and automatic communication.
All commands the relay receives must be of the following form:
<command><CR> or <command><CRLF>
A command transmitted to the relay consists of the command followed by
either a CR (carriage return) or a CRLF (carriage return and line feed). You
can truncate commands to the first three characters. For example, EVENT 1
<Enter> becomes EVE 1 <Enter>. Use upper- and lowercase characters
without distinction, except in passwords.
The relay transmits all messages in the following format:
<STX><MESSAGE LINE 1><CRLF>
<MESSAGE LINE 2><CRLF>
•
•
•
<LAST MESSAGE LINE><CRLF><ETX>
Each message begins with the start-of-transmission character (ASCII 02) and
ends with the end-of-transmission character (ASCII 03). Each line of the
message ends with a carriage return and line feed.
NOTE: The <Enter> key on most
keyboards is configured to send the
ASCII character 13 (<Ctrl+M>) for a
carriage return. This manual instructs
you to press the <Enter> key after
commands to send the proper ASCII
code to the SEL-749M.
Courtesy of NationalSwitchgear.com