S5-115F Manual Introduction to STEP 5
2 Introduction to STEP 5
This chapter explains how to program the S5-115F. 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.
Safety-oriented system configuration
Before you start actual programming, the following safety-oriented procedures should be
observed:
• transfer of safety-oriented operating system parameters (e.g. ”Maximum PLC cycle time”),
• organization and transfer of I/O configuration:
Assignment of I/O types to the reserved I/O addresses and initialization of these I/O types
(e.g. address of the readback digital input module)
• organization and transfer of the SINEC L1 structure to the operating system with the help of
the COM 115F programming package.
2.1 Writing a Program
A control program specifies a sequence of operations that tell the programmable controller (PLC)
how it has to control a system.
You must write the program in a special language and according to
specific rules so that the PLC can ”understand” it. The standard programming language that has
been developed for the SIMATIC S5 family is called STEP 5.
2.1.1 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:
U E 0.1
Operation
Operand
Parameter
Operand ID
002:
Relative address of the statement in a particular block
The operation instructs the PLC what to do with the operand. The parameter indicates the
operand address.
EWA 4NEB 811 6149-02
2-1
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