If

The conditional
If
command provides a way to run a command, or commands, conditionally. The conditional
If
 command can be used wherever other commands can be issued, except that conditional commands cannot be nested. This means that you cannot use an
If
command as the
THEN
 or
ELSE
action for another
If
 command.
Syntax
If <
expression
> THEN <
command
>; <
command
>;... [ELSE<
command
>; <
command
>;... ] ENDIF
where
<expression>
is a comparison (for example, Tag1 = Tag2 or Tag1 = Tag2+Tag3) or any expression that evaluates to a numeric value. An expression that evaluates to any non-zero number will be considered to be True. An expression that evaluates to zero will be considered to be False.
<command>
 is any
FactoryTalk View SE
 command or user-defined macro. Single or multiple commands or macros, separated by semi-colons, can be specified for the THEN or the ELSE action.
Remarks
If the expression evaluates to True, the THEN action is performed. If it evaluates to False and an ELSE action is specified, it will be performed. If the expression evaluates to False and no ELSE action has been specified, no action will be taken.
When using the
If
 command, note that:
  • All parts of the
    If
     command statement must be on a single line.
  • The maximum command length is 5000 characters. The command will be truncated if substituted tag values cause the command to exceed this length.
  • The keywords
    IF
    ,
    THEN
    ,
    ELSE
    , and
    ENDIF
     are not case sensitive.
  • You cannot use the
    IF
    ,
    THEN
    ,
    ELSE
    , or
    ENDIF
    operators in an expression for an
    If
     command.
  • The
    If
    command will be run locally on the HMI Server,
    FactoryTalk View SE
     client, or
    FactoryTalk View Studio
     that issued the command.
  • The commands specified as the
    THEN
     or
    ELSE
     actions will be run where they would normally be run when issued from outside an
    If
     command.
  • The
    If
     command is processed synchronously. This means that when other commands are to be issued after the
    If
     command, for example in a macro, the next command will not be issued until any
    THEN
     or
    ELSE
     commands in the
    If
    command string have been issued, or until an error is encountered in the
    If
     command.
  • If you place an ampersand (
    &
    ) in front of the conditional
    If
     command, the system will not wait for
    THEN
     or
    ELSE
     commands to be run before processing subsequent commands.
  • Do not confuse the
    If
    command with a conditional expression such as you might you create in the
    Expression
     editor. Although both use conditional operators in their structure, you cannot use
    FactoryTalk View SE
    commands as the action for a conditional expression that uses
    IF
    ,
    THEN
    ,
    ELSE
    , or
    ENDIF
     operators.
  • Do not use the alarm functions in the
    Expressions
     editor with the
    If
     command because it will always return a 0 (zero). However, the alarm functions work correctly when used in the
    If-Then_Else
     logic in an expression.
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