UNIT B12.
2 DESCRIBING SIEMENS S7-200/300 PLC SYSTEM
12.2.1Explaining SIEMENS S7-200PLC module and wiring
12.2.1.1 SIEMENS S7-200 CPU module
12.2.1.2 The wiring of SIEMENS S7-200 CPU
The S7-200 series of small PLCs (Micro PLCs) can be used in a variety of automation systems.
The compact construction, low cost and powerful instruction sets make the S7-200 PLC an ideal
solution for a wide range of small control tasks. The variety of S7-200 products and Windows-
based programming tools give you more flexibility in your automation tasks.
The user program of the S7-200 includes bit logic, counters, timers, complex math operations,
and communication with other intelligent modules, so that it can monitor the input state and
change the output state for control purposes. The compact structure, flexible configuration and
powerful instruction set make the S7-200 an ideal solution for a wide range of control
applications.
Introduction of S7-200 series PLC
1. S7-200 series PLC system
CPU 224 type PLC structure
Classification of S7-200 series PLC:
It is divided into two sub-series, CPU 22X and CPU 21X.
Main models of CPU 22X series:
CPU 221 10- I/O points
CPU 222 14-I/O points
CPU 224 24- I/O points
CPU 226 40-I/O points
S7-200 small programmable control system composition:
The S7-200 small PLC consists of a host, also known as a CPU module (basic unit), and I/O
expansion unit, and a functional unit (module) and external equipment (text/graphics display,
programmer), etc.
S7-200 CPU The S7-200 CPU combines a microprocessor, an integrated power supply,
input circuits, and output circuits in a compact housing to create a powerful Micro PLC.
After you have downloaded your program, the S7-200 contains the logic required to
monitor and control the input and output devices in your application.
Siemens provides different S7-200 CPU models with a diversity of features and capabilities that
help you create effective solutions for your varied applications. Table 1-1 briefly compares some
of the features of the CPU
Basic unit types and parameters of the CPU module
Power supply Input Output
type Output voltage
voltage voltage current
DC input 0.75A
24 V DC 24 V DC 24 V DC
DC output transistor
CPU 221
DC input 24 V DC 2A
85 – 264V AC 24 V DC
Relay output 24 – 230V AC relay
CPU 222 DC input 0.75A
24V DC 24 V DC 24 V DC
CPU 224 DC output transistor
CPU 226 DC input
85 – 264V DC 24 V DC 24 – 230V AC 2A, relay
CPU 226XM Relay output
1M and 2M are the common terminals of the input terminals. and -1L and 2L are the common
output terminals.
Figure 1 CPU inputs and outputs unit
Figure 2 CPU 221 wiring diagram
Figure 3 CPU 222 wiring diagram
CPU 224 wiring diagram
CPU 226 wiring diagram
12.2.2 Describing SIEMENS S7-200 expansion module
To better solve your application requirements, the S7-200 family includes a wide variety of
expansion modules. These expansion modules can be used to add additional functionality to the
S7-200 CPU. Table 1-2 provides a list of the expansion modules that are currently available.
12.2.2.1. Digital I/O extension module
Figure 4 wiring diagram for EM 223 expansion modules
12.2.2.2 Analogue I/O expansion module
12.2.2.3 Other extension modules
