Allen-Bradley GuardPLC 1753, Safety Reference Manual

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78 Publication 1753-RM002C-EN-P - September 2008
Chapter 7 GuardPLC Controller Operating System
For the initial start-up of a safety PES or after a modification of the
application program, the safety of the entire system must be checked
by a complete functional test. These three steps must be carried out.
1. Double compilation of the application program followed by
comparison of the code versions (Configuration CRC of the
CPU).
2. Check the correct encoding of the application based on the data
and control flows.
3. Complete functional test of the logic.
See the next section, Check the Created Application Program.
Check the Application Program
To check your application program for adherence to the specific
safety function, you must generate a suitable set of test cases covering
the specification.
As a rule, the independent test of each input and the important links
from the application side should suffice. RSLogix Guard PLUS!
software and the measures defined in this safety manual are designed
to prevent the generation of a semantic and syntactically correct code
that contains undetected systematic errors.
You must also generate a suitable test set for the numeric evaluation
of formulas. Equivalent range tests are acceptable. These are tests
within the defined value ranges, at the range limits, or using invalid
value ranges. Select the test cases to prove the validity of the
calculation. The necessary number of test cases depends on the
formula used and must comprise critical value pairs.
However, active simulation with sources cannot be omitted as it is the
only means of detecting correct wiring of the sensors and actuators
and of testing the system configuration.