Calling a Function
A function ( 
) calculates a result according to the current value
of its inputs. A function has no internal data and is
not linked to declared instances, unlike a function block. A function has only one output: the result of
the function. Examples of standard functions include AND, SHL, SIN, etc..
ST Language
"Structured text"
A high-level language that is block structured and syntactically resembles Pascal, you
have to enter its name, followed by the input parameters written between parentheses and
separated by comas. The function call can be inserted into any complex
expression. A function call can be used as an input parameter of another
function. The following example
demonstrates a call to "ODD" and "SEL" functions:
(* the following statement converts any odd integer value into the nearest even integer *)
iEvenVal := SEL ( ODD( iValue ), iValue, iValue+1 );
FBD and FFLD Languages
To call a function in FBD "Function block diagram"
A function block diagram describes a function between input variables and output variables. A function is described as a set of elementary blocks or FFLD languages, you just
need to insert the function in the diagram and to connect its inputs and output.
IL Language:
To call a function in IL "Instruction list"
This is a low-level language and resembles assembly
language, you must load its first input parameter before the call, and then use
the function name as an instruction, followed by the other input parameters,
separated by comas. The result of the function is then the current result. The following example
demonstrates a call to "ODD" and "SEL" functions:
(* the following statement converts any odd integer into "0" *)
Op1: LD
ODD
SEL iValue, 0
ST iResult
See also:
