Date Code 20010518 Settings 6-29
SEL-2020 Instruction Manual
With both the set and clear elements asserted, there can be no rising edges to trigger operate
commands.
SET U - USER-DEFINED COMMANDS
Use the SET U command to:
• Create user-defined commands that the SEL-2020 will obey.
• Enable handling of a recognized, but unsolicited, SEL relay auto-message.
• Control the SEL-2020 command set.
User-defined commands allow the SEL-2020 to recognize unsolicited inputs. You can create up
to eleven user-defined commands for any Master port, including eight general-purpose and three
special-purpose commands. You can create up to four general-purpose user-defined commands
on SEL IED and other IED ports.
The SEL-2020 has a pre-defined command set (e.g., SHOW, VIEW, SET) that allows you to
control, interrogate, and set the SEL-2020 functions from your computer. If a port is connected
to an unattended device (e.g., an RTU or substation computer), the SEL-2020 pre-defined
command set may be supplemented or replaced by user-defined commands that are appropriate
for the device and function. They are called user-defined because you define the command string
and the action performed by the SEL-2020 when the command is received by the SEL-2020.
These commands are available at all access levels.
On IED ports, the SEL-2020 recognizes unsolicited messages from the IED based on user-
defined message strings you define with the SET U command (e.g., a summary event report from
an SEL relay).
On a Master port, commands are normally terminated with a carriage return (<CR>). The
carriage return is typically sent from a terminal or PC by depressing the Enter key. User-defined
commands on a Master port will similarly be recognized upon receipt of a <CR>. If you disable
the SEL-2020 command set to use only user-defined commands on that port (using the CMD_EN
setting), you may select an alternate command termination character (using the CMD_CH
setting).
General-Purpose Commands
You can set the SEL-2020 so that receipt of a command you defined sets an SEL-2020 database
bit. You can then use that bit in a SEL
OGIC Control Equation to trigger a control action or
message response.
When the SEL-2020 receives a general-purpose user-defined command, it pulses the associated
local element command (CMDx) bit. You may create up to eight general-purpose commands per
port to control the local elements CMD1 through CMD8.
For SEL relays, there are pre-defined auto-messages that you can set the SEL-2020 to recognize,
such as status, summary event reports, and group switch reports. For example, if you define the
first general-purpose command on an SEL IED port to be 20EVENT, the SEL-2020 element
CMD1 on that port pulses when the SEL-2020 receives a summary event report. You use the
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