Step 5 Operations - Siemens SIMATIC S5-100U System Manual

S5-100U
7 Introduction to STEP 5
This chapter explains how to program the S5-100U. It describes how to write a program, how the
program is structured, the types of blocks the program uses, and the number representation of the
STEP 5 programming language.
7.1 Writing a Program
A control program specifies a series of operations that tell the programmable controller how it has to
control a system. For example, a control program might be the series of operations that tell the
S5-100U how to use open-loop control or closed-loop control for a specific system. You must write
the program in a special programming language and according to specific rules so that the pro-
grammable controller can understand it. The programming language that has been developed for the
SIMATIC S5 family is called STEP 5.
7.1.1 Methods of Representation
The following methods of representation are possible with the STEP 5 programming language.
• Statement List (STL)
STL represents the program as a sequence of operation mnemonics. A statement has the
following format:
002:
Relative address of the statement
in a particular block
The operation tells the programmable controller what to do with the operand. The parameter
indicates the operand address.
• Control System Flowchart (CSF)
CSF represents logic operations with graphics symbols.
• Ladder Diagram (LAD)
LAD graphically represents control functions with circuit diagram symbols.
• GRAPH 5, for CPU 103 and higher
GRAPH 5 describes the structure of sequence control systems.
You cannot use CSF, LAD, or GRAPH 5 with the PG 605 programmers.
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Introduction to Step 5
Operation
Operand
Parameter
Operand ID
7-1