Specifications

3 General Programming

3.10 SCL programming language: Tips and tricks

Programming Guideline for S7-1200/1500

V1.2, Entry ID: 81318674

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3.10.4 Efficiently inserting CASE instruction

With the CASE instruction in SCL, it will be exactly jumped to the selected CASE

block condition. After executing the CASE block the instruction is finished. This

allows you, for example, to check frequently required value ranges more

specifically and easily.

Example

CASE #myVar OF

FC5(#myParam);

10,12:

FC10(#myParam);

15:

FC15(#myParam);

0..20:

FCGlobal(#myParam);

// FCGlobal is never called for the values 5, 10, 12 or 15!

ELSE

END_CASE;

3.10.5 No manipulation of loop counters for FOR loop

FOR loops in SCL are pure counter loops, i.e. the number of iterations is fixed

when the loop is entered. In a FOR loop, the loop counter cannot be changed.

With the EXIT instruction a loop can be interrupted at any time.

Advantages

 The compiler can optimize the program better, since it does not know the

number of iterations.

Example

FOR #var := #lower TO #upper DO

#var := #var + 1; // no effect, Compiler -> Warning

END_FOR;