Using Step 7-Micro/Win To Create Your Programs - Siemens Simatic S7-200 System Manual

Using STEP 7–Micro/WIN to Create Your Programs
To open STEP 7–Micro/WIN, double-click on the STEP 7–Micro/WIN icon, or select the Start > SIMATIC >
STEP 7 MicroWIN 3.2 menu command. As shown in Figure 5-1, the STEP 7–Micro/WIN project window
provides a convenient working space for creating your control program.
The toolbars provide buttons for shortcuts to frequently used menu commands. You can view or hide any
of the toolbars.
The navigation bar presents groups of icons for
accessing different programming features of
STEP 7–Micro/WIN.
The instruction tree displays all of the project
objects and the instructions for creating your
control program. You can drag and drop
individual instructions from the tree into your
program, or you can double-click an instruction to
insert it at the current location of the cursor in the
program editor.
The program editor contains the program logic
and a local variable table where you can assign
symbolic names for temporary local variables.
Subroutines and interrupt routines appear as
tabs at the bottom of the program editor window.
Click on the tabs to move between the
subroutines, interrupts, and the main program.
STEP 7–Micro/WIN provides three editors for creating your program: Ladder Logic (LAD), Statement List
(STL), and Function Block Diagram (FBD). With some restrictions, programs written in any of these
program editors can be viewed and edited with the other program editors.
Program
Editor
Features of the STL Editor
The STL editor displays the program as a text-based language. The STL editor allows you to create
control programs by entering the instruction mnemonics. The STL editor also allows you to create
programs that you could not otherwise create with the LAD or FBD editors. This is because you are
programming in the native language of the S7-200, rather than in a graphical editor where some
restrictions must be applied in order to draw the diagrams correctly. As shown in Figure 5-2, this
text-based concept is very similar to assembly language programming.
The S7-200 executes each instruction in the
order dictated by the program, from top to
bottom, and then restarts at the top.
STL uses a logic stack to resolve the control
logic. You insert the STL instructions for handling
the stack operations.
Consider these main points when you select the STL editor:
-
STL is most appropriate for experienced programmers.
-
STL sometimes allows you to solve problems that you cannot solve very easily with the LAD or FBD
editor.
-
You can only use the STL editor with the SIMATIC instruction set.
-
While you can always use the STL editor to view or edit a program that was created with the LAD or
FBD editors, the reverse is not always true. You cannot always use the LAD or FBD editors to
display a program that was written with the STL editor.
Programming Concepts, Conventions, and Features
Instruction tree
Navigation bar
Figure 5-1 STEP 7–Micro/WIN
LD I0.0
A I0.1
= Q1.0
Figure 5-2 Sample STL Program
Chapter 5
Program Editor
//Read one input
//AND with another input
//Write value to output 1
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