User manual

IEC61131 User and Reference Manual
April 22, 2008
1
Overview
Control Microsystems IEC 61131-3 implementation enables the programming of
SCADAPack controllers using the IEC 61131-3 programming languages. The programming
environment uses the ISaGRAF Workbench to create, load and debug IEC 61131-3
application programs.
Supported Languages
ISaGRAF Workbench supports the five standard IEC 61131-3 programming languages and
a sixth language called Flow Chart. These languages may be mixed and matched within an
application to provide an optimum control strategy. The supported programming languages
are described below.
Sequential Function Chart (SFC)
The Sequential Function Chart is a graphic language used to describe sequential operations
in a process. The process is graphically partitioned into a set of well-defined steps containing
actions performed using other languages such as ST, IL, LD and FBD. Steps are linked
together with conditional transitions. This language is useful for batch processes and
process procedures such as automatic startup and shut down.
Functional Block Diagram (FBD)
The Function Block Diagram is a graphic language used to build complex procedures from a
library of functions. Standard library functions such as math and logic may be combined with
custom library functions such as dial up modem control, HART Interface, PID controllers and
Modbus master and slave protocols to create Function Block Diagram application programs.
A class of programs called functions allows the creation of user functions that are not
included in the library.
Ladder Diagram (LD)
Ladder Diagram is a graphic language combining contacts and coils to build logical discrete
control procedures. This language is identical to the relay ladder logic used by most
programmable Logic Controllers. Ladder Diagram contacts and coils may be used in the
Function Block Diagram language for discrete control of functions.
Structured Text (ST)
Structured Text is a high-level structured language, similar to Pascal and C, that is used for
complex procedures or calculation that cannot be easily implemented using graphic
languages. Structured Text is the default language used to describe actions within the steps
of the Sequential Function Chart language.
Instruction List (IL)
Instruction List is a low-level programming language, similar to assembly language that is
used in small applications that require fast execution. This language is typically used to
optimize sections of an application.
Flow Chart (FC)
Flow Chart is a graphic language that is used to describe sequential operations in an
application. A Flow Chart diagram is composed of actions to be performed and tests on the
actions performed. Actions and tests are connected by oriented links, representing data flow
through the Flow Chart. Tests determine the yes or no path of the data flow.
Custom Functions
The standard ISaGRAF Workbench is enhanced with custom functions to support features
provided by the SCADAPack controllers. Custom functions provide support for dial up