Allen-Bradley GuardPLC 1753, Safety Reference Manual

Page: 86 / 120

86 Publication 1753-RM002C-EN-P - September 2008
Chapter 8 Technical Safety for the Application Program
General Procedure
The general procedure for programming the GuardPLC control
systems for technical safety applications is listed below.
•
Specify the control function.
•
Write the application program.
•
Compile the application program with the C-code generator.
•
Translate the C-code twice and compare the results.
•
Generate an error-free, executable program.
•
Verify and validate.
The program can then be tested by the user and the PES can initiate
safety operation.
Basis of Programming
The application program should be:
•
easy to understand.
•
easy to trace.
•
easy to change.
•
easy to test.
The control task should be available as a specification or a
performance specification. This documentation forms the basis for the
check of correct transformation into the program. The presentation of
the specification depends on the application task to be carried out.
This can be:
•
combinatory logic.
•
sequential controls (step controls).
•
digital or analog sensors.
•
actuators.
Combinatory Logic
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Cause/effect diagram
•
Logic of the link with functions and function modules
•
Function blocks with specified characteristics