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Rockwell Automation Publication 1756-RM093J-EN-P - April 2018
Chapter 6
Safety Application Development
Once application program testing is complete, you must generate the safety task
signature. The programming software automatically uploads the safety task
signature after it is generated.
You can delete the safety task signature only when the GuardLogix controller is
safety-unlocked and, if online, the keyswitch is in the REM or PROG position.
When a safety task signature exists, the following actions are not permitted
within the safety task:
•
Online or offline programming or editing of safety components
•
Forcing Safety I/O
•
Data manipulation (except through routine logic or another GuardLogix
controller)
Project Verification Test
To check the application program for adherence to the specification, you must
generate a suitable set of test cases covering the application. The set of test cases
must be filed and retained as the test specification.
You must include a set of tests to prove the validity of the calculations (formulas)
used in your application logic. Equivalent range tests are acceptable. These are
tests within the defined value ranges, at the limits, or in invalid value ranges. The
necessary number of test cases depends on the formulas used and must comprise
critical value pairs.
Active simulation with sources (field devices) must also be included, as it is the
only way to verify that the sensors and actuators in the system are wired correctly.
Verify the operation of programmed functions by manually manipulating sensors
and actuators.
You must also include tests to verify the reaction to wiring faults and network
communication faults.
Project verification includes required functional verification tests of fault
routines, and input and output channels, to be sure that the safety system operates
properly.
To perform a functional verification test on the GuardLogix controller, you must
perform a full test of the application. You must toggle each sensor and actuator
involved in every safety function. From a controller perspective, this means
toggling the I/O point going into the controller, not necessarily the actual
activators. Be sure to test all shutdown functions, because these functions are not
typically exercised during normal operation. Also, be aware that a functional
verification test is valid only for the specific application tested. If the controller is
IMPORTANT
To verify the integrity of every download, you must manually record the
safety task signature after initial creation and check the safety task
signature after every download to make sure that it matches the original.
