Considerations When Using the Loop Component

The Loop component allows you to execute subflows while incrementing a parameter's value.

Before you use the Loop component, it is important to understand the following information:

  • You cannot select parameter types other than the selected parameter type for expression formation or value substitution. For example, if you have a For Each loop with a real parameter, you cannot select a string parameter as one of its values; you can select only another real parameter. The only exception is that you can select integer parameters when the loop variable is real.

  • Proper loop execution requires that the parameters (iteration parameter in For and For Each loops, and condition parameters in While and Do Until loops) are mapped correctly between the parent loop and its subflows.

  • For While and Do Until loops to function properly, all parameters that are used in the conditions and that are expected to change their values during iterations must be input/output parameters. In this case their values are preserved from one iteration to another by the Loop component. For example, when creating a While loop with the condition (N < 10) and a calculator in the subflow with the expression N = N + 1, you must ensure that parameter N is an input/output parameter in both the Loop component and the Calculator component and that the parameter is mapped in both directions. If this is not done, parameter N's values are always reset to the initial value at every calculator execution, and the loop ends up executing infinitely or until it reaches the maximum number of iterations.

  • For all loops except For Array loops, the values of all output or input/output parameters after the loop finishes are taken from the last iteration (highest run number, not the last iteration to finish). Only the For Array loop’s output arrays allow the values of other iterations to be mapped to subsequent components.