ON

Statement - Conditional execution of statements.

Syntax

ON <BOOL expression> DO
   <statements>
END_DO;

Remarks

• 
  

• This instruction is NOT UDFB "User Defined Function Block" UDFB can be used as a sub-function block in another program of the application. It is described using FBD, LD, ST or IL language. Input / output parameters of a UDFB (as well as private variables) are declared in the variable editor as local variables of the UDFB safe.
  Do not use inside UDFBs.

• The ON instruction:
  • Provides a simpler syntax for checking the rising edge A rising edge is the transition of a digital signal from low to high. It is also called positive edge of a Boolean condition.
  • Avoids systematic use of the R_TRIG function block or other "last state" flags.
• Statements within the ON structure are executed only when the Boolean expression rises from FALSE to TRUE.
• The ON syntax is available in any program or sub-program.
• This statement is an extension to the standard and is NOT IEC "International Electrotechnical Commission" IEC is a not-for-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies 61131-3 compliant.

FBD Language Example

Not available.

FFLD Language Example

Not available.

IL Language Example

Not available.

ST Language Example

(* This example counts the rising edges of variable bIN *)
ON bIN DO
   diCount := diCount + 1;
END_DO;