Updating an Application on the PLC CODESYS basically provides two options to transfer a modified application to the controller: download and online change. A download results in a recompilation of the

ST Comments Comment Description Example Single-line There are two ways of marking: Starts with // and ends at the end of the line Starts with /// and ends at the end of the line In CODESYS , these com

Variables The scope of a variable defines how and where you can use a variable. You define the scope in the variable declaration. :

Variable: VAR_INPUT Input variables are used at the inputs of function blocks. You declare VAR_INPUT variables between the VAR_INPUT and END_VAR keywords in the declaration part of POUs. When called,

Variable: VAR_OUTPUT Output variables are used at the outputs of function blocks. You declare VAR_OUTPUT variables between the VAR_OUTPUT and END_VAR keywords in the declaration part of POUs. The valu

Variable: VAR_IN_OUT A VAR_IN_OUT variable is an input/output variable, which is part of a POU interface and serves as a formal pass-by-reference parameter. Syntax <keyword> <POU name> VAR_IN_OUT <var

Variable: VAR_GLOBAL Important If a local variable that is declared in a block has the same name as a global variable, then it has precedence within the block. Important For compiler version 3.2.0.0 a

ST Statement: IF The IF statement is used for checking a condition and, depending on this condition, for executing the subsequent statements. A condition is coded as an expression that returns a Boole

ST Statement: FOR The FOR loop is used to execute statements with a certain number of repetitions. Syntax: FOR <counter> := <start value> TO <end value> {BY <increment> } DO <instructions> END_FOR; Th

ST Statement: CASE The CASE statement is a conditional control structure which causes a statement or a section of a statement to be executed only under a specific condition. The section which is execu