Date Code 20010518 General Description 2-1
SEL-2020 Instruction Manual
SECTION 2: GENERAL DESCRIPTION
INTRODUCTION
The SEL-2020 Communications Processor provides many special features needed in today’s sub-
stations to communicate with a variety of microprocessor-based devices. The SEL-2020 can
function as a simple, but intelligent, port switch. Or it can provide sophisticated communication
and data handling capability required for advanced substation integration projects. The
following pages describe the SEL-2020’s features and their benefits to the user.
BASIC (BUT POWERFUL) FUNCTIONS
The SEL-2020's unique design and powerful features make it useful for a variety of functions. It
can serve as an intelligent port switch, a synchronizing time source, a communications processor,
a SEL
OGIC
®
Control Equations programmable controller, and an automatic database.
• Intelligent Port Switch
: The SEL-2020, in its most basic role, is a port switch. Several
features of the SEL-2020 improve significantly on that role, such as its multi-tasking/ multi-
user capability, auto-configuration, wide range of settable baud rates (300 baud to 38400
baud), and complete selection of communication parameters (data bits, parity, stop bits,
RTS/CTS, and XON/XOFF).
• Synchronizing Time Source
: The SEL-2020 distributes a demodulated IRIG-B signal
through Ports 1 to 16. This signal can be used by any attached device that recognizes the
IRIG-B code simply by your connecting the proper cable to the SEL-2020. The signal can be
distributed to SEL relays that accept IRIG-B input, simply by using a special cable designed
for both communication and IRIG-B signals. The SEL-2020 internally generates the IRIG-B
signal, unless you connect an external source of modulated or demodulated IRIG-B to the
SEL-2020. If the connected device does not accept IRIG-B, you can program the SEL-2020
to send a date and time message to the device.
• Communications Processor:
The SEL-2020 can send and receive message strings and
codes in several different formats, permitting communication with a variety of devices,
including SEL relays, PCs, modems, RTUs, printers, other IEDs, and other SEL-2020s. The
built-in command set facilitates communication to and through the SEL-2020 using any
communication software that supports ASCII “dumb terminal” emulation. You can also
develop user-defined command strings to communicate to and from non-SEL devices. The
SEL-2020 can also communicate as a slave on a Modbus RTU or DNP V3.00 network. This
feature makes the SEL-2020 a convenient network device, which communicates to a master
device through flexible connections such as point-to-point and daisy chain.
• SEL
OGIC Control Equations Programmable Controller: The SEL-2020 includes
powerful SEL
OGIC Control Equations that can be used to trigger messages, commands, and
control functions.
• Automatic Database
: The SEL-2020 is unique in its ability to receive, parse, store, and dis-
tribute data. The SEL-2020 automatically parses data from SEL relays. Several parsing
options are available to parse data from devices other than SEL relays. Selected portions of
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