Schweitzer Engineering Laboratories SEL-421-4 - Page 1293

15.23
Date Code 20171006 Instruction Manual SEL-400 Series Relays
Communications Interfaces
SEL Protocol
Virtual Serial Ports
Actual serial ports are described in Serial Port Hardware Protocol on page 15.5.
In addition to actual serial ports, the relay supports several virtual serial ports. A
virtual serial port does the following:
➤ Transmits and receives characters through a different mechanism
than the physical serial port
➤ “Encapsulates” characters in virtual terminal messages of a different
protocol
➤ Simulates an actual serial port with setting PROTO := SEL
➤ May have restrictions imposed by the protocol that encapsulates the
virtual serial data
You can set the relay to use virtual serial ports encapsulated in SEL M
IRRORED
B
ITS communications links, DNP3 links, and through Telnet over Ethernet.
SEL Protocol
This subsection describes the command sets that are active when the port setting
PROTO := SEL. You can also access these protocols through virtual serial ports
that simulate ports with PROTO := SEL.
SEL ASCII Commands
SEL originally designed the SEL ASCII commands for communication between
the relay and a human operator via a keyboard and monitor or a printing terminal.
A computer with a serial port can also use the SEL ASCII protocol to communi-
cate with the relay, collect data, and issue commands.
The ASCII character set specifies numeric codes that represent printing charac-
ters and control characters. The complete ASCII command set is shown in
Section 14: ASCII Command Reference. Table 15.17 shows the subset of the
ASCII control characters used in this section.
PMU Phasor Measurement Unit Binary Synchrophasor Protocol, as selected
by Port Setting PMUMODE and Global Setting
MFRMT (see Section 18: Synchrophasors).
PMU SEL Fast Operate Binary operation commands
RTD SEL Fast Message protocol
for Resistance Temperature
Detector (RTD) data
As many as 12 analog temperature readings
from the SEL-2600A.
DNP DNP3 Level 2 Outstation Binary commands and responses (see
Section 16: DNP3 Communication).
Table 15.16 Supported Serial Command Sets (Sheet 2 of 2)
PROTO Setting
Value
Command Set Description
NOTE: Not all SEL-400 series
relays support synchrophasors (the
PMU protocol choice).
NOTE: Not all SEL-400 series relays
support RTD communications with
the SEL-2600A.