HIMax Safety Manual - Tuv-fs.com

10 User program HIMaxSensors (digital or analog)• Signals during normal operation ('de-energize-to-trip' principle with digital sensors, 'lifezero'with analog sensors)• Signals in the event of a fault:Definition of required safety-related redundancies (1oo2, 2oo3)(see Chapter )• Discrepancy monitoring and reactionActuators• Positioning and activation during normal operation• Safe reaction/positioning at shutdown or after power lossProgramming goals for user program• Easy to understand.• Easy to trace and follow.• Easy to test.• Easy to modify.10.2.2 Functions of the User ProgramProgramming is not subject to hardware restrictions. The user program functions can befreely programmed.When programming, account for the 'de-energize-to-trip' principle for the physical inputsand outputs. Only elements complying with IEC 61131-3 together with their functionalrequirements are permitted within the logic.• The physical inputs and outputs usually operate in accordance with the 'de-energize-totrip'principle, i.e. their safe state is "0“.• The user program includes meaningful logic and/or arithmetic functions irrespective ofthe 'de-energize-to-trip' principle of the physical inputs and outputs.• The program logic should be clear and easy to understand and well documented toassist in debugging. This includes the use of functional diagrams.• To simplify the logic, the inputs and outputs of all function blocks and variables can beinverted in any given order.• The programmer must evaluate the fault signals from the inputs/outputs or from logicblocks.The "packaging" of functions in self-created function blocks and functions consisting ofstandard functions is reccommended. This ensures that a user program can be clearlystructured in modules (functions, function blocks). Each module can be viewed and testedon its own. By grouping smaller modules into larger ones and then all together into a singleuser program, the user is effectively creating a comprehensive, complex function.10.2.3 System Parameters of the User ProgramThe following user program switches and parameters can be set in the Properties dialogbox of the user program:Page 54 of 70HI 801 003 D Rev.2.0