Quick Start Owner's manual

Publication 1756-QS001E-EN-P - October 2009 107
Document a Project Chapter 6
Comments in Structured Text
To make your structured text easier to interpret, add comments. Comments:
• let you use plain language to describe how your structured text works.
• download to the controller and upload from the controller.
• do not affect the execution of the structured text.
Follow these steps to add comments to your structured text.
Here is an example.
To add a comment Use one of these formats
On a single line //comment
(*comment*)
/*comment*/
At the end of a line of structured text
Within a line of structured text (*comment*)
/*comment*/
That spans more than one line (*start of comment . . . end of
comment*)
/*start of comment . . . end of
comment*/
Format Example
//comment At the beginning of a line
//Check conveyor belt direction
IF conveyor_direction THEN...
At the end of a line
ELSE //If conveyor isn’t moving, set alarm light
light := 1;
END_IF;
(*comment*) Sugar.Inlet[:=]1;(*open the inlet*)
IF Sugar.Low (*low level LS*)& Sugar.High (*high level
LS*)THEN...
(*Controls the speed of the recirculation pump. The
speed depends on the temperature in the tank.*)
IF tank.temp > 200 THEN...
/*comment*/ Sugar.Inlet:=0;/*close the inlet*/
IF bar_code=65 /*A*/ THEN...
/*Gets the number of elements in the Inventory array
and stores the value in the Inventory_Items tag*/
SIZE(Inventory,0,Inventory_Items);