Siemens Simatic S7-200 CPU 210, Системное руководство

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4-9
S7-200 Programmable Controller, CPU 210
C79000-G7076-C235-01
4.4 Understanding the Programming Languages
The CPU 210 and STEP 7-Micro/WIN support the following programming languages:
S
Statement list (STL) is a set of mnemonic instructions that represent functions of the
CPU.
S
Ladder is a graphical language that resembles the electrical relay diagrams for the
equipment.
STEP 7-Micro/WIN also provides two representations for displaying the addresses and the
programming instructions in the program: International and SIMATIC. Both the international
and SIMATIC representations refer to the same CPU 210 instruction set. There is a direct
correspondence between the International and the SIMATIC representation; both
representations have the same functionality.
Understanding the Basic Elements of Ladder
When you write a program in ladder, you create and arrange the graphical components to
form a network of logic. As shown in Figure 4-7, the following types of elements are available
for creating your program:
S
Contacts: each of these elements represents a switch through which power can flow
when a switch is closed.
S
Coils: each of these elements represents a relay that is energized by power flowing to
that relay.
S
Boxes: each of these elements represents a function that is executed when power flows
to the box.
S
Networks: this element forms a complete circuit. Power flows from the left power rail
through the closed contacts to energize the coils or boxes.
Output Coils Output
F4 F5 F8 F7 F6 F10
F3 F2
I0.0 I0.1 Q0.0
Network
Left Power Rail
Network 2
T0 I0.0
IN
PT
TON
+0
Box
Network 1
Network
NETWORK TITLE (single line)
Coil
NETWORK TITLE (single line)
Normally Open
Contact Normally Closed
Contact
Figure 4-7 Basic Elements of Ladder
Basic Concepts for Programming the CPU 210