Transitions

There is a horizontal line indicating transition below the step:

The Boolean expression can act as transition condition. The transition is executed if two following conditions are met:

1) transition is permitted (corresponding step is active);

2) transition condition is TRUE.

Only transition type identifier is displayed on the chart. Condition is described in separate window in ST language. In conditional expression of transition, one can not employ assignment operation. Partially painted transition corner is the indicator that transition identifier is a separately implemented condition and not a logical variable.

The Boolean constant can be assigned as a transition condition. If TRUE is assigned, the step is executed once in one complete cycle. Then control system comes to the next step. If the FALSE condition is assigned, step is executed endlessly.

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