Program structure

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Program structure
Logics
Conditions
Loops
Step sequences
Subroutines
DLL-Interface

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Program structure

In order to meet the various requirements of modern automation systems, MPC Solution offers different kinds of programming, which are arbitrarily combinable with one another, offering new possibilities. The Soft-PLC part of the system consists of so-called machines and subroutines. Those subroutines are re-usable and seperately storable program sections whose parameters can be changed. A machine consists of pre-defined program modules for manual and automatic operations, for initialization, two switching off routines and a continuous program. Because of the predefinition, only the assigned on-, off-, manual- and automatic push buttons must be assigned when being assumed. A program modul consists of variables, conditions, loops and sequences.

Components of the program structure

Program structure

Logics

Conditions

Loops

Step sequences

Subroutines

DLL-Interface

Logics

The logic functions correspond in the first instance to the classical PLC. MPC Solution thus also presents the functionality of a PLC. Extensions were accomplished in areas where new functionality facilitates the programming.

Logics consist of a arbitrary number of operations. Operations which are put down into logics, are processed with each program cycle. A logic can also be implemented conditionally. For the program structuring conditions and loops were implemented.

Conditions

These special operations process an instruction if a condition is true. The "if" and "switch-case" conditions can be found in programming languages like C, JAVA, or VB, and also in MPC-Solution. They are giving a good oppurtunity to structure your program. In the separated folders (THEN, ELSE, CASE, DEFAULT) other logics, operations and step sequences can be implemented.

For this, the normal "if (then else)" condition and a "switch (case default)" element is available.

If the condition from this at "if" indicated variable is true, this element will be executed. I.e. all operations which are agreed underneath this folder, will be activated.
If the condition from this at "if" indicated variable is not true, no execution will take place. I.e. all operations which are agreed underneath this folder, will not be activated.

switch

This operation processes an instruction if a certain value complies to the "Switch" variable. The "case" element of a "Switch case" unit is implemented, if the indicated value applies. I.e. all operations which are agreed underneath this folder, will be activated. The "Default" element of a "Switch case" unit is implemented, if no "case" value applies. I.e. all operations which are agreed underneath this folder, will be activated.

Loops

The loops operate as long as their stopping condition is true. This kind of commands is well known in other programming languages like C, JAVA or VB.

for	The "For" - loop increases and/or decreases the counter step-by-step until reaching the final value.
while	This loop is accomplished until the condition of "While" gets WRONG.
do while	The "Do-While" - loop is at least once passed through, until the condition of "Do-While" gets WRONG.

Step sequences

Step sequences frequently appear in almost every application and have proven themselves in this system. A step sequence consists of any number of steps. Every step has its condition to move to the next step and any number of logics and/or operations. Because only the active step is worked off, this construction helps saving processing time.

Subroutines

You can also use all operations now in subroutines. The status of each call-instance can now be displayed. You need no longer help variables in operations because there are new parameter types. You can store subroutines as reusable components on disk and reuse them afterwards in other applications.

DLL-Interface

A DLL-Interface is used to call specific functions, which are deposited in a DLL (library). Parameters from MPC-Solution can be given to the DLL - these are evaluated resp. processed by the DLL - and a return value passes back. In this case it is not important whether the DLL was written in C or VB.

In the software folder you can insert a new interface by opening the context menu with the right mouse button. After clicking on the newly created DLL-Interface you can now insert the function through opening the context menu. Finally, when the name, the call convention and the process is determined, the return value and parameters to the DLL can be assigned in the parameter box.