Automatic control function programming manual ladder language

16.1 General
Programming in C Language
Programming the automatic control function in C has the following advantages:
- the programmes are structured (use of explicit variable names, language syntax, data structure, character strings,
etc.)
- libraries of functions can be used (management of character strings, arithmetic, etc.)
- the user can write function libraries available for use by several applications.
All the tasks can be written in C.
All the variables of the exchange area are accessible to programmes written in C.
Functions exec(..) and exechdl(..) are used to manage the C executables resulting from the C compiler in a ladder
module.
! CAUTION
When a pointer is used, it must be correctly initialised. If this check is not made, there is a
risk of generating a "prohibited address" fault.
For instance, the return code of the MALLOC function must be tested before using the
address returned by the function.
16.2 Call Executable Module exec
Syntax
exec(whexec, {arg }6 )
whexec: Logic identifier of the executable module to be called.
arg: Arguments (if any), extended on 32 bits and passed via the stack.
Calls an executable module generated from a C-language compiler.
Principle
The (signed) arguments arg are extended on 32 bits and stacked in accordance with the C-language convention (the
first argument is at the top of the stack). whexec is not stacked.
The logic identifier whexec is provided by function exechdl().
The system analyses whexec and calls the associated executable module.
Return code
If OK
The value returned by the C-language executable module.
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