Schweitzer Engineering SEL-387-0, Instruction Manual

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7.7
Date Code 20170601 Instruction Manual SEL-387-0, -5, -6 Relay
Serial Port Communications and Commands
Communications Protocol
Communications Protocol
This section explains the serial port communications protocol used by the
SEL-387. You set and operate the SEL-387 via the serial communications
ports.
Relay output appears boxed and in the following format:
XFMR 1 Date: 02/01/97 Time: 11:03:25.180
The communications protocol consists of hardware and software features.
Hardware Protocol
All EIA-232 serial ports support RTS/CTS hardware handshaking. RTS/CTS
handshaking is not supported on the EIA-485 serial port.
To enable hardware handshaking, use the SET P command (or front-panel
{SET}
pushbutton) to set RTSCTS = Y. Disable hardware handshaking by
setting RTSCTS = N.
If RTSCTS = N, the relay permanently asserts the RTS line.
If RTSCTS = Y, the relay deasserts RTS when it is unable to receive
characters.
If RTSCTS = Y, the relay does not send characters until the CTS input is
asserted.
Software Protocol
Software protocols consist of standard SEL ASCII, SEL Distributed Port
Switch (LMD), SEL Distributed Network Protocol (DNP), SEL Fast Meter,
SEL Fast Operate, and SEL Compressed ASCII. Based on the port
PROTOCOL setting, the relay activates SEL ASCII, SEL LMD, or SEL DNP
protocol. SEL Fast Meter and SEL Compressed ASCII commands are always
active.
SEL ASCII Protocol
The following software protocol is designed for manual and automatic
communications.
1. All commands received by the relay must be of the form:
<command><CR> or <command><CR><LF>
A command transmitted to the relay should consist of the
following:
➤
A command followed by either a carriage return or a carriage
return and line feed.
➤
You must separate arguments from the command by spaces,
commas, semicolons, colons, or slashes.
➤
You may truncate commands to the first three characters.
EVENT 1 <Enter> would become EVE 1 <Enter> .
➤
Upper- and lowercase characters may be used without
distinction, except in passwords.