Calling a Sub-Program
A sub-program is called by another program. Unlike function blocks, local variables of a sub-program are not instantiated, and thus you do not need to declare instances. A call to a sub-program processes the block algorithm using the specified input parameters. Output parameters can then be accessed.
ST Language
MySubProg (i1, i2); (* calls the sub-program *)
Res1 := MySubProg.Q1;
Res2 := MySubProg.Q2;
Alternatively, if a sub-program has one and only one output parameter, it can be called as a function in ST language:
Res := MySubProg (i1, i2);
FBD and FFLD Languages
To call a sub-program 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 block in the diagram and to connect its inputs and outputs.
IL Language
To call a sub-program in IL"Instruction list" This is a low-level language and resembles assembly language, you must use the CAL instruction with the name of the sub-program, followed by the input parameters written between parentheses and separated by comas. Alternatively the CALC, CALCN or CALNC conditional instructions can be used:
CAL Calls the sub-program
CALC Calls the sub-program if the current result is TRUE
CALNC Calls the sub-program if the current result is FALSE
CALCN same as CALNC
Here is an example:
Op1: CAL MySubProg (i1, i2)
FFLD MySubProg.Q1
ST Res1
FFLD MySubProg.Q2
ST Res2