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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3.10.6 FOR loop backwards

In SCL you can also increment the index of FOR loops backwards or in another

step width. For this, use the optional “BY” key word in the loop head.

Example

FOR #var := #upper TO #lower BY -2 DO

END_FOR;

If you are defining “BY” as “-2”, as in the example, the counter is lowered by 2 in

every iteration. If you omit “BY”, the default setting for “BY” is 1

3.10.7 Simple creating of instances for calls

If you prefer to work with the keyboard, there is a simple possibility to create

instances for blocks in SCL.

Example

Table 3-13: Easy creation of instances

Step Instruction

1. Give the block name a: followed by a "." (dot). The automatic compilation now

shows you the following.

2. On the top you can see the already existing instances. In addition, you can

directly create a new single instance or multi-instance.

Use the shortcuts "s" or "m" to go directly to the respective entries in the

automatic compilation window.

3.10.8 Handling of time tags

You can calculate the time tags in SCL just as with normal numbers i.e. you do not

need to look for additional functions, such as, e.g. T_COMBINE but you can use

simple arithmetic. This approach is called “overload of operands”. The SCL

compiler automatically uses the suitable functions. You can use a reasonable

arithmetic for the time types and can therefore program more efficiently.

Example

TimeDifference := TimeStamp_1 – TimeStamp_2;