Application of the add-on block library Function Chart - all rights reserved - Dr. Geitner ETI/TU Dresden

Example 10 - Simple failure handling with branching

Static test of a failure handling with branching. The normal functional sequence consists of a loop with the states X100, X10, X20 and X30. It is possible to simulate a fictitious failure by means of the manual FEHLER switch. Depending on the pre-state of the functional sequence one of the three failure handling states X1, X2 or X3 gets active as a response to the failure. After the fictitious elimination of the failure assigned manual QUIT_x switches allow a return to the normal functional sequence. Thus the function charts for normal sequence and failure handling may be programmed completely separately from each other. The transitions (connections) back to the normal sequence are realized directly for this simple example. Connector blocks may also be used advantageously as shown in examples 5 and 6. As a result, a totally graphical separation is obtained. The re-entry points to the function chart for normal functional sequence are freely selectable in accordance with the technological requirements. Each failure handling sequence (path) has to start with exactly one FVZ block; exception: no branch - no FVZ block necessary. After that event-dependent branches may appear.