Use conditional program branching structures

You can dynamically control the execution path of a script based on certain conditions being met. The InTouch HMI supports IF-THEN-ELSE control structures for this purpose.

The basic syntax for an IF-THEN-ELSE control structure is as follows:

Syntax

IF Condition THEN

... statements and/or another IF-THEN-ELSE structure

[ELSE

... statements and/or another IF-THEN-ELSE structure]

ENDIF;

Remember the following rules when working with IF-THEN-ELSE structures:

• IF-THEN-ELSE structures can be nested, both in the THEN section and in the ELSE section.

• For every IF statement, there must be a closing ENDIF statement. An ENDIF statement always applies to the nearest prior IF statement on the same nesting level.

• Condition must be a valid discrete expression. The THEN section is executed if Condition is TRUE. The ELSE section is executed if Condition is FALSE.

• The ELSE section is optional.

• Some other programming languages allow you to check multiple conditions on the same hierarchy level of an IF-THEN-ELSE structure and have one general ELSE section that is executed if all of the conditions evaluate to FALSE. (The If-ElseIf-Else structure in Visual Basic is an example of this.) This is not possible in the InTouch HMI. For every condition to check, you must open a new IF-THEN-ELSE structure. Therefore, to have a single section of code to act as the ELSE code for all conditions, you must place it in the ELSE section of the IF-THEN-ELSE structure at the last nesting level.