7-2 SELOGIC Control Equations Date Code 20010518
SEL-2020 Instruction Manual
Messages are triggered by the rising edge (or assertion) of the trigger condition bit. You can use
output messages for the following tasks:
• Request data from an IED.
• Send a command to an IED (to change setting groups, for example).
• Send data you want stored to a printer or master device.
In addition to inputs and outputs, there are five intermediate logic variables. You can use these
variables to write equations, the results of which may be used in output equations. Three
intermediate elements have pickup and dropout delay timers associated with them.
INPUTS
As shown in Figure 7.1, there are a number of different types of SELOGIC Control Equation
inputs. These include global elements, local elements, relay elements, relay status information,
arbitrary database bits, and timed conditions.
Global Elements
Global elements exist within the Global data region that is common to all Port databases. Items
within this region include the day of the week, remote bits, intermediate SEL
OGIC Control
Equation terms, and I/O board inputs and outputs. These elements are defined in Section 9:
Database. Global elements are referenced in SEL
OGIC Control Equations by their element
names. For example, you would enter the Sunday day-of-week element in a SEL
OGIC Control
Equation as SUN.
Local Elements
Local elements exist within the Local data region of each port’s database. Some of these
elements are asserted by user-defined command receipt, some by select-before-operate registers,
some by SEL
OGIC Control Equations, and others by data collection operation. These elements
are defined in Section 9: Database. To use a local element in a logic equation, you must give
both its Port number and label. For example, to access element D1 on Port 3, the element label
to use is 3:D1. If the SEL
OGIC Control Equation you are writing is port-specific, the Port for
elements on that Port need not be specified.
Relay Elements
SEL relay elements are available on any SEL relay port that is collecting element data (uses
20TARGET data collection). Each element may be specified by its element label, preceded by
the Port number. For example, to access relay element 51NT on Port 4, you use 4:51NT. If the
element name matches a local or global element, you must specify the region to identify the
proper element (e.g., 4:TARGET:IN1). If you write a port-specific equation, the Port for the
desired relay element is in the local port, and the relay element label is unique from any local and
global elements, then you do not need to specify the Port number. You can view the relay
element labels by using the TAR n ALL, MAP n TARGET BL, or VIEW n TARGET BL
commands.
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