R.5.3
Date Code 20111215 Reference Manual SEL-421 Relay
SEL Communications Protocols
Protocol Active When Setting PROTO := SEL
Virtual Serial Ports
Actual serial ports are described in Serial Port Hardware Protocol on
page R.5.1. In addition to actual serial ports, the SEL-421 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 SEL-421 to use virtual serial ports encapsulated in SEL
M
IRRORED BITS communications links, DNP3 links, and through the Telnet
mechanism of an installed Ethernet card.
Protocol Active When Setting PROTO := SEL
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 communicate with the relay, collect data, and issue commands.
The ASCII character set specifies numeric codes that represent printing
characters and control characters. The complete ASCII command set is shown
in Section 9: ASCII Command Reference in the Reference Manual. Tab le 5. 3
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 Synchrophasors on
page R.7.1
PMU SEL Fast Operate Binary operation commands
RTD SEL Fast Message
protocol for Resistance
Temperature Detector
(RTD) data
Up to 12 analog temperature readings from
the SEL-2600A.
DNP DNP3 Level 2 Slave Binary commands and responses. See
Section 6: DNP3 Communications in the
Reference Manual
Table 5.2 Supported Serial Command Sets (Sheet 2 of 2)
PROTO
Setting Value
Command Set Description
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