C to SCL

AutoGen_3490985

Hello everyone,

I was wondering if there is any easy way to convert a C script in SCL. If you know something like this, please let me know. 

 The complexity of the code will be the deciding factor. It becomes ugly when using C++ with object orientated program structures. A good place to start is to convert the C (C++?) to Pascal. Some web searches may be helpful to complete this 1st step.

Hi,

SCL and Pascal are closely based on the IEC EN 61131-3 standard but it's not the same code, only similar.

I don´t know any converter.

Regards,

Towome

AutoGen_3490985

 is it similar to SCL?

Quite. For sure Pascal syntax is closer to SCL syntax than C syntax is.

However some basic knowledge of syntax of both is required to adjust Pascal code to meet SCL rules.

It kind of depends on the complexity of the c code.

The PLC has largely analogous data types, so any data types should read across without much issue. Type definitions and structures are supported in SCL. Unions are not, but a degree of equivalency can be engineered using data overlays (the AT construct).

Program flow control statements again are largely analogous. IF, THEN, ELSE, SWITCH, GOTO, REPEAT/UNTIL, DO/WHILE, FOR/NEXT etc should cover most c code statements.

The PLC has pointers but they are NOT the same or are as flexible or powerful as their c equivalents. Pointer arithmetic could be covered by using disassembled ANY pointers / PEEK / POKE instructions.

Functions can be replaced with FB / FC. However, you can forget function pointers as they really can't be emulated. Recursion is also not permissible in the PLC.

So if you have a good knowledge of both programming languages and also the function / purpose of the c code and it is not too complex, you should have a reasonable chance of success. However, it is unlikely to be a quick exercise.

I think I would be reasonably confident that I could convert some simple c code to SCL.

smiffy

<snip>
Recursion is also not permissible in the PLC.
</snip>

@smiffy: Good day Sir. Your statement does not hold true anymore. Recursive functions is now possible. Step7 V14 or later for the S7-1200 and S7-1500, up to the maximum nesting depth. (So yes.. it is limited.)

For your reference please have a look at the following post:
Simple Sample: Recursive functions