Siemens Simatic S7 Manuals and Guides

Siemens Simatic S7 Manuals and Guides
Siemens
Simatic S7
Manuals and Guides
Presented By: Siemens Supply
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Siemens S7 Manuals
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Table of Contents
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Introduction...............................................................................2
PLCs..........................................................................................4
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Number Systems.......................................................................8
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Terminology............................................................................. 2
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Basic Requirements................................................................. 8
S7-200 Micro PLCs..................................................................20
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Programming a PLC.................................................................33
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Discrete Inputs/Outputs..........................................................4
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Analog Inputs and Outputs......................................................48
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Timers......................................................................................5
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Counters..................................................................................58
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High-Speed Instructions..........................................................6
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Specialized Expansion Modules..............................................65
Review Answers......................................................................72
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Final Exam............................................................................... 74
Introduction
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Welcome to another course in the STEP series, Siemens
Technical Education Program, designed to prepare our
distributors to sell Siemens Industry, Inc. products more
effectively. This course covers Basics of PLCs and related
products.
Upon completion of Basics of PLCs you should be able to:
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Identify the major components of a PLC and describe
their functions
Convert numbers from decimal to binary, BCD, and
hexadecimal
Identify typical discrete and analog inputs and outputs
Identify key differences of the various S7-200 models
Identify the types of expansion modules available for
S7 200 PLCs
Describe the types or programming available for S7-200
PLCs
Describe the operation of commonly used program
functions such as timers and counters
Identify the proper manual to refer to for programming or
installation of an S7-200 PLC
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This knowledge will help you better understand customer
applications. In addition, you will be better able to describe
products to customers and determine important differences
between products. You should complete Basics of Electricity
before attempting Basics of PLCs. An understanding of many
of the concepts covered in Basics of Electricity is required for
this course.
After you have completed this course, if you wish to determine
how well you have retained the information covered, you can
complete a final exam online as described later in this course. If
you pass the exam, you will be given the opportunity to print a
certificate of completion.
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Siemens is a trademark of Siemens AG. Product names
mentioned may be trademarks or registered trademarks of their
respective companies. Specifications subject to change without
notice.
PLCs
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A programmable logic controller (PLC), also referred to as
a programmable controller, is the name given to a type of
computer commonly used in commercial and industrial control
applications. PLCs differ from office computers in the types of
tasks that they perform and the hardware and software they
require to perform these tasks. While the specific applications
vary widely, all PLCs monitor inputs and other variable values,
make decisions based on a stored program, and control
outputs to automate a process or machine. This course is
meant to supply you with basic information on the functions
and configurations of PLCs with emphasis on the S7-200 PLC
family.
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Motor
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Indicator Light
The basic elements of a PLC include input modules or points,
a central processing unit (CPU), output modules or points,
and a programming device. The type of input modules or
points used by a PLC depends upon the types of input devices
used. Some input modules or points respond to digital inputs,
also called discrete inputs, which are either on or off. Other
modules or inputs respond to analog signals. These analog
signals represent machine or process conditions as a range of
voltage or current values. The primary function of a PLC’s input
circuitry is to convert the signals provided by these various
switches and sensors into logic signals that can be used by the
CPU.
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Pump
Pushbutton
Sensor
Basic PLC Operation
SF/DIAG
The CPU evaluates the status of inputs, outputs, and other
variables as it executes a stored program. The CPU then sends
signals to update the status of outputs.
Output modules convert control signals from the CPU into
digital or analog values that can be used to control various
output devices.
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The programming device is used to enter or change the PLC’s
program or to monitor or change stored values. Once entered,
the program and associated variables are stored in the CPU.
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In addition to these basic elements, a PLC system may also
incorporate an operator interface device to simplify monitoring
of the machine or process.
Central Processing Unit
(CPU)
Output
Module
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Input
Module
Operator
Interface
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Programming
Device
Motor
Motor Starter
Output
SF/DIAG
PLC
Inputs
Start
Stop
Pushbutton Pushbutton
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In the simple example shown below, pushbuttons (sensors)
connected to PLC inputs are used to start and stop a motor
connected to a PLC output through a motor starter (actuator).
No programming device or operator interface are shown in this
simple example.
Prior to PLCs, many control tasks were performed by
contactors, control relays, and other electromechanical devices.
This is often referred to as hard-wired control. Circuit
diagrams had to be designed, electrical components specified
and installed, and wiring lists created. Electricians would then
wire the components necessary to perform a specific task. If
an error was made, the wires had to be reconnected correctly.
A change in function or system expansion required extensive
component changes and rewiring.
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T2
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T3
L1
460 VAC
L2
L3
T1
Motor
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24 VAC
Start
CR
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Stop
2
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Hard-Wired Control
PLCs not only are capable of performing the same tasks as
hard-wired control, but are also capable of many more complex
applications. In addition, the PLC program and electronic
communication lines replace much of the interconnecting wires
required by hard-wired control. Therefore, hard-wiring, though
still required to connect field devices, is less intensive. This also
makes correcting errors and modifying the application easier.
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Advantages of PLCs
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Smaller physical size than hard-wire solutions.
Easier and faster to make changes.
PLCs have integrated diagnostics and override functions.
Diagnostics are centrally available.
Applications can be immediately documented.
Applications can be duplicated faster and less expensively.
Siemens SIMATIC PLCs are the foundation upon which our
Totally Integrated Automation (TIA) concept is based.
Because the needs of end users and machine builders vary
widely, SIMATIC PLCs are available as conventional modular
controllers, embedded automation products, or as PC-based
controllers.
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Some of the additional advantages of PLCs are as follows:
SIMATIC
S7-1200
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Modular SIMATIC controllers are optimized for control tasks
and can be adapted to meet application requirements using
plug-in modules for input/output (I/O), special functions, and
communications. Examples of products in this category include:
LOGO!, S7-200, and S7- 200 micro automation products,
S7-300 and S7-400 modular system PLCs, C7 combination
controller and panel, and ET 200 distributed I/O system with
local intelligence.
SIMATIC S7-1200
LOGO!
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SIMATIC S7-200
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SIMATIC S7-300
SIMATIC embedded automation products are available in
a microbox, panel PC, or multi-functional PC-based system.
All products utilize rugged, fan-free, diskless hardware
platforms with an operating system optimized for each
platform. Examples of products in this category include:
Microbox 420 RTX, Microbox 420-T, Panel PC 477-HMI/RTX, and
WinAC MP.
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SIMATIC PC-based controllers are available as software that
can run on standard PC systems or in a plug-in card (slot PLC)
for increased reliability. This category includes WinAC software
and WinAC slot PLC.
SIMATIC software is the universal configuring and
programming environment for SIMATIC controllers, human
machine interface systems, and process control systems.
SIMATIC software with STEP 7 and numerous engineering
tools supports all phases of product deployment, from
hardware configuration of the system and parameterization
of modules to service of the installed system. A variety
of programming options are available. This includes basic
programming languages (Instruction List, Ladder Diagram,
and Function Block Diagram), high-level languages (Structured
Text and Sequential Function Chart), and engineering tools
(S7 Structured Control Language, S7-Graph, S7-PLCSIM, S7HiGraph, and Continuous Function Chart).
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SIMATIC Software
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Other SIMATIC Controllers
SIMATIC S7-400
Number Systems
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In order to understand the binary number system, it is
first useful to recall some of the basics of the decimal
number system. All number systems have the same three
characteristics: digits, base, weight. For example, the decimal
system has the following characteristics:
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1
1
1
1
0,
2
Powers of base 2 ( , 2, 4, 8, 6, ...)
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1 1 The binary system has a base of 2 and uses only two
characters, and 0. Each bit is associated with a power of 2
based on its position in the number. The further to the left,
the higher the power of 2. The number in the far left-hand
column is referred to as the most significant bit or MSB and
the number in the far right-hand column is referred to as the
least significant bit or LSB. A is placed in a position if that
power of 2 is used in the number. Otherwise, a 0 is placed in a
position.
Most Significant Bit (MSB)
Least Significant Bit (LSB)
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26
25
24
23
22
21
20
128
64
32
16
8
4
2
1
0
0
0
1
1
0
0
0
00011000 in binary = 24 in Decimal
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Two digits:
Base
Weights
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The binary system has the following characteristics:
Binary System
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1
0, , 2, 3, 4, 5, 6, 7, 8, 9
0
Powers of base 0 ( , 0, 00, 000, ...)
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Ten digits
Base
Weights
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Decimal System
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Because a PLC is a computer, it stores information in the form
of on or off conditions ( or 0), referred to as bits. Sometimes
bits are used individually and sometimes they are used
to represent numerical values. Understanding how these
bits can be used to represent numerical values requires an
understanding of the binary number system.
1 The process of converting a binary number to an equal decimal
value is as simple as adding the equivalent decimal value
for each position in the binary number where a is shown.
Positions with a 0 do not add to the number value.
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25
24
23
22
21
20
128
64
32
16
8
4
2
1
0
0
1
0
1
0
0
1
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Each position in a binary number is called a bit. The number
of bits used to represent numbers varies with the device.
However, instructions and data are usually grouped in bytes and
eight bits make up one byte. Two bytes, or 6 bits, make up one
word.
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Bit
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Bits, Bytes, and Words
Decimal Value = 32 + 8 + 1 = 41
Byte
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While PLCs are capable of sensing and generating analog
values, programmable controllers internally use signals that are
on or off. These on and off conditions correspond to the binary
values and 0. For example, a binary 0, also called logic 0, can
be used to indicate that a switch is off, and a binary (logic )
can be used to indicate that a switch is on.
Off
Logic 0
PLC
24 VDC
On
Logic 1
PLC
24 VDC
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1
1 Input 1
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Logic 0, Logic 1
Word
BCD
While it is necessary for PLCs to use binary values, humans
often need to see values represented in decimal. As a result,
some input and output devices provide a decimal display where
each decimal digit corresponds to four PLC binary inputs or
outputs. The most common system used by input and output
devices of this type is referred to as binary-coded decimal
(BCD).
0010
0000
0101
0
0
0
0
0
0
0
0
1
1
BCD
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
0 0 0
0 0 1
The hexadecimal system is used in PLCs because it allows the
status of a large number of binary bits to be represented in a
small space such as on a computer screen or programming
device display. Each hexadecimal character represents the exact
status of four binary bits.
Hexadecimal Number System
16 digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F
Base
16
Weights Powers of base 16 (1, 16, 256, 4096, ...)
Hexadecimal Example
Binary Equivalent
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Hexadecimal is another system used in PLCs. The ten digits
of the decimal system are used for the first ten characters of
the hexadecimal system. The first six letters of the alphabet are
used for the remaining six characters.
Hexadecimal
Decimal
0
1
2
3
4
5
6
7
8
9
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0000
0
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0
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One example of a BCD device is a type of four-digit
thumbwheel switch. Each thumbwheel digit controls four
PLC inputs. This means that for a four-digit thumbwheel, 6
inputs are required. Because each thumbwheel digit only
needs to represent decimal values from 0 through 9, only ten
corresponding binary values are required for each digit.
0
3
A
2
F
0 0 1 1 1 0 1 0 0 0 1 0 1 1 1 1
Hexadecimal
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
Binary
0 0 0 0
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0 1 0 1
0 1 1 0
0 1 1 1
1 0 0 0
1 0 0 1
1 0 1 0
1 0 1 1
1 1 0 0
1 1 0 1
1 1 1 0
1 1 1 1
Identify each of the following blocks in a basic PLC
system:
b. ______________
a. ______
e. _______
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d. _______
c. ______
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Review 1
3.
The base of the hexadecimal number system is ___.
4.
Convert the decimal number 0 to each of the following
number types:
BCD
____________
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Hexadecimal
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Binary
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The base of the binary number system is ___ .
2.
____________
Terminology
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Developing an understanding of PLCs requires learning
some basic terminology. This section provides an overview of
commonly used PLC terms, beginning with the terms sensor
and actuator.
Sensors are devices that convert a physical condition into an
electrical signal for use by a controller, such as a PLC. Sensors
are connected to the input of a PLC. A pushbutton is one
example of a sensor that is often connected to a PLC input. An
electrical signal indicating the condition (open or closed) of the
pushbutton contacts is sent from the pushbutton to the PLC.
Actuators
Actuators are devices that convert an electrical signal from a
controller, such as a PLC, into a physical condition. Actuators are
connected to the PLC output. A motor starter is one example of
an actuator that is often connected to a PLC output. Depending
on the status of the PLC output, the motor starter either
provides power to the motor or prevents power from flowing to
the motor.
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Sensors
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Discrete Input
Sensor
Input
Point
Discrete Output
Actuator
PLC
Central
Processing
Unit
(CPU)
Output
Point
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Pushbutton
Motor
Starter
Motor
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Discrete Inputs and Outputs Discrete inputs and outputs, also referred to as digital
inputs and outputs, are either on or off. Pushbuttons, toggle
switches, limit switches, proximity switches, and relay contacts
are examples of devices often connected to PLC discrete
inputs. Solenoids, relay and contactor coils, and indicator lamps
are examples of devices often connected to PLC discrete
outputs.
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In the on condition, a discrete input or output is represented
internal to the PLC as a logic . In the off condition, a discrete
input or output is represented as a logic 0.
2
1
Analog inputs and outputs are continuous, variable signals.
Typical analog signals vary from 0 to 20 milliamps, 4 to
20 milliamps, or 0 to 0 volts.
Analog Inputs and Outputs
Panel
Meter
PLC
Central
Processing
Unit
(CPU)
Analog
Input
Analog
Output
0
0.2
0.4
0.6
0.8
1.0
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Level
Transmitter
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In the following example, a level transmitter monitors the level
of liquid in a storage tank and sends an analog signal to a PLC
input. An analog output from the PLC sends an analog signal to
a panel meter calibrated to show the level of liquid in the tank.
Two other analog outputs, not shown here, are connected to
current-to-pneumatic transducers that control air-operated flowcontrol valves. This allows the PLC to automatically control the
flow of liquid into and out of the storage tank.
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Storage
Tank
The central processor unit (CPU) is a microprocessor system
that contains the system memory and is the PLC’s decisionmaking unit. The CPU monitors inputs, outputs, and other
variables and makes decisions based on instructions held in its
program memory.
I0.0
I0.4
SF/DIAG
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CPU
1
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I0.5
3
I0.1
Q0.0
Q0.1
Ladder Logic Programming
A program consists of instructions that accomplish specific
tasks. The degree of complexity of a PLC program depends
upon the complexity of the application, the number and type of
input and output devices, and the types of instructions used.
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Ladder logic (LAD) is one programming language used with
PLCs. Ladder logic incorporates programming functions that are
graphically displayed to resemble symbols used in hard-wired
control diagrams.
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The left vertical line of a ladder logic diagram represents the
power or energized conductor. The output coil instruction
represents the neutral or return path of the circuit. The right
vertical line, which represents the return path on a hard-wired
control line diagram, is omitted. Ladder logic diagrams are read
from left-to-right and top-to-bottom. Rungs are sometimes
referred to as networks. A network may have several control
elements, but only one output coil.
I0.1
Q0.0
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Network 1 I0.0
Normally Open Contact Instructions
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Power Conductor
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Network 2
Q0.0
I0.5
While ladder logic programs are still common, there are many
other ways to program PLCs. Two other common examples are
statement list and function block diagrams.
Statement list (STL) instructions include an operation and an
operand. The operation to be performed is shown on the left.
The operand, the item to be operated on, is shown on the right.
Function block diagrams (FBD) include rectangular functions
with inputs shown on the left side of the rectangle and outputs
shown on the right side.
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Statement List and
Function Block Diagrams
Output Coil Instruction
4
Statement List (STL)
Function Block Diagram (FBD)
Network 1
Network 1
LD I0.0
A I0.1
= Q0.0
I0.0
AND
I0.1
Q0.0
Q0.0
Network 2
I0.4
I0.5
Q0.1
I0.1
Network 2
I0.4
I0.4
I0.5
OR
Q0.1
Q0.0
I0.5
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LD
O
=
Network 1
I0.0
Network 2
Ladder Logic (LAD)
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In the following example, the program segments perform the
same function.
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In addition to LAD, STL, and FBD, multiple other types of
programming languages are used for PLCs. Each type of
programming has its advantages and disadvantages. Factors
such as application complexity, types of programming available
for a specific PLC model, and user standards and preferences
determine which type of programming is used for an
application.
The PLC program is executed as part of a repetitive process
referred to as a scan. A PLC scan starts with the CPU
reading the status of inputs. Next, the application program is
executed. Then, the CPU performs internal diagnostics and
communication tasks. Finally, the CPU updates the status of
outputs. This process repeats as long as the CPU in the run
mode. The time required to complete a scan depends on the
size of the program, the number of I/Os, and the amount of
communication required.
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on
sti c
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Co
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Pr
PLC Scan
ate
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Inp
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PLC Scan
5
1
1
1
1
1
1
1
Kilo, abbreviated k, normally refers to 000 units. When talking
about computer or PLC memory, however, k means 024. This
0
is because of the binary number system (2 = 024). k can refer
to 024 bits, bytes, or words, depending the context.
Memory Types and Size
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Random Access Memory (RAM) is memory that allows data
to written to and read from any address (location). RAM is used
as a temporary storage area. RAM is volatile, meaning that
the data stored in RAM will be lost if power is lost. A battery
backup is required to avoid losing data in the event of a power
loss.
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Read Only Memory (ROM) is a type of memory used were
it is necessary to protect data or programs from accidental
erasure. The original data stored in ROM can be read, but
not changed. In addition, ROM memory is nonvolatile. This
means that information will not be lost as the result of a loss of
electrical power. ROM is normally used to store the programs
that define the capabilities of the PLC.
Software is the name given to computer instructions,
regardless of the programming language. Essentially, software
includes the instructions or programs that direct hardware.
Hardware is the name given to all the physical components
of a system. The PLC, the programming device, and the
connecting cable are examples of hardware.
Firmware is user or application specific software burned into
EPROM and delivered as part of the hardware. Firmware gives
the PLC its basic functionality.
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Software, Hardware, and
Firmware
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Erasable Programmable Read Only Memory (EPROM)
provides a level of security against unauthorized or unwanted
changes in a program. EPROMs are designed so that data
stored in them can be read, but not easily altered. Changing
EPROM data requires a special effort. UVEPROMs (ultraviolet
erasable programmable read only memory) can only be erased
with an ultraviolet light. EEPROM (electronically erasable
programmable read only memory), can only be erased
electronically.
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Putting it Together
The user memory of a PLC, such as the S7-200 PLC shown in
the following illustration, includes space for the user program as
well as addressable memory locations for storage of data. The
amount of program and data space available depends on the
CPU model.
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User program space stores instructions that are executed
repetitively as part of the PLC scan. The user program is
developed using a programming device, such as a personal
computer (PC) with programming software, then loaded into the
user program memory of the PLC.
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A variety of addressable memory locations are used for storage
of data that is available to the user program. Among other
things, this includes memory locations for variable data, discrete
inputs and outputs, analog inputs and outputs, timers, counters,
high-speed counters, etc.
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I0.0
7
I0.4
I0.5
I0.1
Q0.0
Q0.1
Basic Requirements
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Throughout this course we will be using the S7-200 PLC for
specific examples of PLC concepts. The S7-200 PLC is used
for this purpose because of its ease of use and wide-spread
application.
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The items shown in the following illustration are needed to
create or change an S7-200 PLC program. The program is
created using STEP 7-Micro/WIN programming software,
which runs on a Windows-based personal computer (Win2000,
Windows XP, and higher operating system).
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A special cable is needed when a personal computer is used as
a programming device. Two versions of this cable are available.
One version, called an RS-232/PPI Multi-Master Cable,
connects a personal computer’s RS-232 interface to the PLC’s
RS-485 connector. The other version, called a USB/PPI MultiMaster Cable, connects a personal computer’s USB interface
to the PLC’s RS-485 connector.
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Programming Device
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Software
STEP 7 - Micro/WIN
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Programming Device Cable
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SF/DIAG
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S7-200 PLC
8
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Pushbuttons, limit switches, and relay contacts are
examples of devices that may be connected to PLC
____________ inputs.
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Review 2
Solenoids, relay and contactor coils, and indicator lamps
are examples devices that may be connected to PLC
___________ outputs.
3.
The _____ contains the system memory and makes
decisions based on instructions stored in program
memory.
4.
______ _____ is a PLC programming language that
incorporates programming functions that are graphically
displayed to resemble symbols used in hard-wired
control diagrams.
5.
_________ ____ and ________ _____ ________ are also
common examples of ways to program a PLC.
6.
A PLC program is executed as part of a repetitive
process referred to as a ____.
7.
When talking about computer or PLC memory, k refers
to ______ bits, bytes, or words.
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8.
An RS-232/PPI Multi-Master cable or a USB/PPI-MultiMaster cable may be used to connect a personal
computer to an S7-200 PLC’s __________ connector.
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9.
Software that is burned into EPROM is called
____________.
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S7-200 Micro PLCs
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The S7-200 Micro PLC is the smallest member of the SIMATIC
S7 family of programmable controllers.
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Each S7-200 central processing unit (CPU) model also includes
input and output points in the same housing as the CPU.
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Inputs and outputs (I/O) are the system control points. Inputs
monitor field devices, such as switches and analog sensors.
Outputs control other devices, such as motors and control
valves.
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The programming port is the connection to the programming
device and also provides a means for connecting the PLC to
other devices, such as display panels.
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Model Description
221 D C /D C /D C
221 A C /D C /R elay
222 D C /D C /D C
222 A C /D C /R elay
224 D C /D C /D C
224 A C /D C /R elay
224XP D C /D C /D C
Power Supply
20.4-28.8 V D C
85-264 V A C , 47-63 H z
20.4-28.8 V D C
85-264 V A C , 47-63 H z
20.4-28.8 V D C
85-264 V A C , 47-63 H z
20.4-28.8 V D C
Input Types
6 x 24 V D C
6 x 24 V D C
8 x 24 V D C
8 x 24 V D C
14 x 24 V D C
14 x 24 V D C
14 x 24 V D C , 2 x A nalog
Output Types
4 x 24 V D C
4 x R elay
6 x 24 V D C
6 x R elay
10 x 24 V D C
10 x R elay
10 x 24 V D C , 1 x A nalog
224XP A C /D C /R elay
85-264 V A C , 47-63 H z
14 x 24 V D C , 2 x A nalog
10 x R elay, 1 x A nalog
224XP si D C /D C /D C
20.4-28.8 V D C
14 x 24 V D C , 2 x A nalog
10 x 24 V D C (current sinking),
1 x A nalog
226 D C /D C /D C
226 A C /D C /R elay
20.4-28.8 V D C
85-264 V A C , 47-63 H z
24 x 24 V D C
24 x 24 V D C
16 x 24D C
16 x R elay
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There are six S7-200 CPU types (CPU 221, CPU 222, CPU 224,
CPU 224XP, CPU 224XPsi, and CPU 226) and two power
supply configurations for each type.
S7-200 Models
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SF/DIAG
20
Comm Ports
1
1
1
1
1
1
2
2
2
2
2
In the model description, the first term following the CPU type
indicates the power supply type, the second term indicates
the input type, and the third term indicates the output type.
For example, a 222 AC/DC/Relay model is powered from an AC
source, has DC input points, and relay contact output points.
1
CPU 221
CPU 222
CPU 224
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Feature
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The S7-200 family includes a range of CPUs which provide
a variety of features to aid in designing a cost-effective
automation solution. The accompanying table provides a
summary of the major features, many of which are covered in
this course. Note that the CPU 224XPsi has 0 current sinking
digital outputs, but its other features are the same as for the
CPU 224XP.
S7-200 Features
CPU 224XP
CPU 226
CPU 224XPsi
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Memory
4096 Bytes
4096 Bytes
8192 Bytes
12288 Bytes
16384 Bytes
Program (w/o run mode edit)
4096 Bytes
4096 Bytes
12288 Bytes
16384 Bytes
24576 Bytes
User Data
2048 Bytes
2048 Bytes
8192 Bytes
10240 Bytes
10240 Bytes
Optional Memory Cartridges
64k or 256k Bytes 64k or 256k Bytes
64k or 256k Bytes
64k or 256k Bytes
64k or 256k Bytes
Memory Backup (super cap)
50 Hours typical
50 Hours typical
100 Hours typical
100 Hours typical
100 Hours typical
Memory Backup (opt. battery)
I/O
200 Days typical
200 Days typical
200 Days typical
200 Days typical
200 Days typical
Digital I/O without Exp. Modules
6 In/4 Out
24 In/16 Out
None
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Program (with run mode edit)
14 In/10 Out
14 In/10 Out
None
None
Max Expansion Modules
Instructions
None
2
7
2 In/1 Out
7
7
Internal Relays
256
256
256
256
256
Counters
256
256
256
256
256
TImers
256
256
256
256
256
32-Bit, Floating-Point Math (+-*/) Yes
Enhanced Features
High-Speed Counters
4 (30 KHz)
Yes
Yes
Yes
Yes
4 (30 KHz)
6 (30 KHz)
6 (30 KHz)
Pulse Outputs (DC)
2 (20 KHz)
2 (20 KHz)
2 (20 KHz)
4 (30 KHz),
2 (200 KHz)
2 (20 KHz)
2 (1ms - 255ms)
4
2 (1ms - 255ms)
4
2 (1ms - 255ms)
4
2 (1ms - 255ms)
4
2 (1ms - 255ms)
4
Optional
Optional
Built-In
Built-In
Built-In
Yes
Yes
Yes
Yes
Yes
1 (RS-485)
1 (RS-485)
1 (RS-485)
2 (RS-485)
2 (RS-485)
PPI, MPI Slave,
Freeport
Not Expandable
PPI, MPI Slave,
Freeport
PROFIBUS DP Slave,
AS-Interface Master,
Ethernet, Internet,
Modem
PPI, MPI Slave,
Freeport
PROFIBUS DP Slave,
AS-Interface Master,
Ethernet, Internet,
Modem
PPI, MPI Slave,
Freeport
PROFIBUS DP Slave,
AS-Interface Master,
Ethernet, Internet,
Modem
PPI, MPI Slave,
Freeport
PROFIBUS DP Slave,
AS-Interface Master,
Ethernet, Internet,
Modem
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Password Protection
Communications
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Number of Ports
Protocols Supported Port 0
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Optional Communcations
2
1
Real-Time Clock
.s
Timed Interrupts
Edge Interrupts
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8 In/6 Out
Analog I/O without Exp. Modules None
2 (20 KHz)
Depending on the CPU model, an S7-200 CPU is powered from
either a 24 VDC or a 20 to 240 VAC power supply. For example,
an CPU 22 DC/DC/DC model is powered from a 24 VDC power
supply and a CPU 222 AC/DC/Relay model is powered from a
20 or 240 VAC power supply.
1
1 1
Power Sources
AC Voltage Source
120 to 240 VAC
(Nominal Voltage)
Each S7-200 CPU has a mode switch with three positions,
RUN, STOP, and TERM. When the mode switch is in the
RUN position, the CPU is in the RUN mode and executing the
program, unless a fault has occurred. When the mode switch
is in the STOP position, the CPU is in the STOP mode and
not executing the user program. When the mode switch is in
the TERM position, the programming device can select the
operating mode.
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Mode Switch and Analog
Adjustment
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DC Voltage Source
24 VDC
(Nominal Voltage)
22
SF/DIAG
Analog
Adjustment
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212-1BB23-0XB0
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Mode
Switch
up
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The CPU status indicators display the current CPU mode.
When the CPU is in the RUN mode, the green RUN indicator
is lit. When the CPU is in the STOP mode, the yellow STOP
indicator is lit. The System Fault/Diagnostic (SF/DIAG)
indicator turns red for a system fault and yellow to indicate
certain diagnostic conditions.
CPU Status
Indicators
IAG
SF/D
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CPU Status Indicators
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An analog adjustment is available to increase or decrease
values stored in special memory. This can allow a variable in the
user program to change as the analog adjustment is changed.
CPU 22 and CPU 222 models have one analog adjustment.
CPU 224, CPU 224XP, CPU 224 XPsi, and CPU 226 have two
analog adjustments.
The I/O status indicators represent the on or off status of
corresponding inputs and outputs. For example, when the CPU
senses an input is on, the corresponding green indicator is lit.
23
S7-200 CPUs support an optional memory cartridge that
provides portable EEPROM storage for the user program. The
cartridge can be used to copy a program from one S7-200 PLC
to a like S7-200 PLC. Two memory cartridge sizes are available,
64k and 256k bytes.
Optional Cartridges
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1 Two other cartridges are also available. A real-time clock with
battery is available for use on the CPU 22 and CPU 222. (CPU
224, CPU 224XP, CPU 224XPsi, and CPU 226 have a real-time
clock built in.) The battery provides up to 200 days of data
retention time in the event of a power loss. Another cartridge is
available with a back-up battery only.
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SF/DIAG
24
Input devices, such as switches, pushbuttons, and other
sensors are connected to the terminal strip under the bottom
cover of the PLC.
Inputs and Outputs
Local Output Points
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Output Devices
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SF/DIAG
SF/DIAG
Input Devices
Input Simulator
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Local Input Points
Output devices, such as relays, are connected to the terminal
strip under the top cover of the PLC. When testing a program,
it is not necessary to connect output devices. The LED status
indicators signal if an output is active.
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A convenient method of testing a program is to wire toggle
switches to the inputs. Input simulators with pre-wired toggle
switches are available for use with S7-200 PLCs. Switches are
wired between the 24 VDC power supply (L+) and the inputs.
For example, the switch on the far left is wired between the
first input (0.0) and L+. When the switch is closed, 24 VDC is
applied to the input. When the switch is open, 0 VDC is applied
to the input.
25
1 An optional fan-out connector allows field wiring connections
to remain fixed when removing or replacing a CPU 22 or
CPU 222. The appropriate connector slides into either the input,
output, or expansion module terminals.
Field Wiring
Optional Fan-out Connector
for CPU 221 or CPU 222
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Connector Posts
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CPU 224, CPU 224XP, and CPU 226
Removeable Terminal Strip
A super capacitor, so named because of its ability to maintain
a charge for a long period of time, protects data stored in RAM
in the event of a power loss.
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RAM
(Volatile)
Executed
Program
Current
Data
Super Capacitor
Memory
Bits,
Timers,
Counters
26
1
1 The RAM memory is typically backed up for 50 hours on the
CPU 22 and CPU 222 and for 00 hours on the CPU 224, CPU
224 XP, CPU 224 XPsi, and CPU 226.
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Super Capacitor
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CPU 224, CPU 224XP, CPU 224XPsi, and CPU 226 do not have
an optional fan-out connector. Instead, their terminal strips are
removable.
EEPROM
(Non-volitle)
Program
Backup
Parameters
Optional EEPROM
Memory Cartridge
(Non-volatile)
Program
and
Parameters
Expansion Modules
S7-200 PLCs are expandable by adding expansion modules.
Expansion modules with inputs and/or outputs are connected
to the base unit using a ribbon connector.
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SF/DIAG
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SF/DIAG
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The ribbon connector is protected by a cover on the base unit.
Side-by-side mounting completely encloses and protects the
ribbon connector.
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Mounting
S7-200 PLCs can be mounted in one of two ways. A DIN clip
allows installation on a standard DIN rail. The DIN clip snaps
open to allow installation and snaps closed to secure the
unit on the rail. The S7-200 can also be panel mounted using
installation holes located behind the access covers.
Din Rail
27
Most S7-200 expansion modules are designed to provide
additional I/O. However, several expansion modules are available
to support communication options, positioning, and weighing
(SIWAREX MS).
Available Expansion
1 CPU 22 comes with 6 discrete inputs and 4 discrete outputs
and does not accept expansion modules.
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CPU 222 comes with 8 discrete inputs and 6 discrete outputs
and accepts up to 2 expansion modules.
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CPU 224, CPU 224XP, and CPU 224XPsi come with 4 discrete
inputs and 0 discrete outputs and accept up to 7 expansion
modules. Note: The digital outputs for the CPU 224XPsi are
current sinking.
1
6 Inputs, 4 O utputs
N o E xpansion M odules (E M )
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C P U 221
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CPU 226 comes with 24 discrete inputs and 6 discrete
outputs and accepts up to 7 expansion modules.
8 Inputs, 6 O utputs
EM
C P U 224
EM
EM
U p to 2 E xpansion M odules
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C P U 222
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EM
EM
C P U 226
EM
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C P U 224XP
C P U 224XP si
EM
EM
14 Inputs, 10 O utputs
EM
EM
EM
EM
EM
EM
EM
EM
EM
EM
U p to 7 E xpansion M odules
14 Inputs, 10 O utputs
2 A nalog In, 1 A nalog O ut
U p to 7 E xpansion M odules
24 Inputs, 16 O utputs
EM
EM
EM
EM
EM
U p to 7 E xpansion M odules
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E xpansion M odules
D iscrete Input
8 x 24 V D C
8 x 120/230 V A C
16 x 24 V D C
D iscrete O utput
4 x 24 V D C
8 x 24 V D C
8 x 120/230 V A C
D iscrete C om bination
4 x 24 V D C In/4 x 24 V D C out
8 x 24 V D C In/8 x 24 V D C O ut
16 x 24 V D C In/16 x 24 V D C O ut
32 x 24 V D C In/32 x 24 V D C O
4 x 24 V D C In/4 x R elay
8 x 24 V D C In/8 x R elay
16 x 24 V D C In/16 x R elay
32 x 24 V D C In/32 x R elay
4 x A nalog
4 x T herm ocouple
2 x RTD
8 x A nalog
8 x T herm ocouple
4 x RTD
A nalog O utput
2 x A nalog
4 x A nalog
A nalog C om bination
4 x A nalog In/1x A nalog O ut
C om m unication M odules
M odem
A nalog Input
A S -Interface
G S M /G P R S M odem
O ther M odules
P osition
S IW A R E X M S
28
P R O F IB U S -D P
4 x R elay
E thernet
8 x R elay
E thernet IT
S7-200 inputs and outputs are labeled at the wiring terminations
and next to the status indicators. These alphanumeric symbols
identify the I/O address to which a device is connected. This
address is used by the CPU to determine which input is present
and which output needs to be turned on or off.
I/O Numbering
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I designates a discrete input and Q designates a discrete
output. The first number identifies the byte, the second number
identifies the bit.
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Image register space for digital I/O is always reserved in
increments of eight bits (one byte). If a module does not
provide a physical point for each bit of each reserved byte,
these unused bits cannot be assigned to subsequent modules
in the I/O chain.
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Each analog I/O point is associated with a 6-bit word in the
S7-200 PLC and is identified by AI (for analog input) or AQ
(for analog output) followed by a W (representing a word of
memory) and a starting byte number. Analog I/O words start on
even-numbered bytes (such as 0, 2, or 4).
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Analog I/O points are always allocated in increments of two
points. If a module does not provide physical I/O for each of
these points, these I/O points are lost and are not available for
assignment to subsequent modules in the I/O chain.
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The following example shows the addressing for one sample
application.
CPU 224XP
Module 0
Module 1
Module 2
Module 3
Module 4
14 D iscrete In 10 D iscrete O ut
2 A nalog In
1 A nalog O ut
I0.1
I0.2
I0.3
4 D iscrete O ut
8 D iscrete In 4 A nalog In 1 A nalog O ut 8 D iscrete O ut
Q 2.0
I3.0
A IW 4
AQW 4
Q 3.0
A IW 12
AQW 8
Q 0.1
I2.1
Q 2.1
I3.1
A IW 6
AQW 6
Q 3.1
A IW 14
A Q W 10
Q 0.2
I2.2
Q 2.2
I3.2
A IW 8
Q 3.2
A IW 16
Q 0.3
I2.3
Q 2.3
I3.3
A IW 10
Q 3.3
A IW 18
Q 0.4
I2.4
Q 2.4
I3.4
Q 3.4
I0.5
Q 0.5
I2.5
Q 2.5
I3.5
Q 3.5
I0.6
Q 0.6
I2.6
Q 2.6
I3.6
Q 3.6
I0.7
Q 0.7
I2.7
Q 2.7
I3.7
Q 3.7
I1.0
Q 1.0
E xpansion I/O
I1.1
Q 1.1
I1.2
Q 1.2
I1.3
Q 1.3
I1.4
Q 1.4
I1.5
Q 1.5
I1.6
Q 1.6
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4 A nalog In 1 A nalog O ut
I2.0
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I0.4
4 D iscrete In
Q 0.0
.s
I0.0
I1.7
Q 1.7
A IW 0
AQW 0
A IW 2
AQW 2
A ddresses show n w ith a black background are not available and cannot be used in the program .
Local I/O
29
Siemens offers a variety of SIMATIC Micro Panels designed for
use with S7-200 PLCs. These panels provide easy to implement
solutions for a variety of display needs.
SIMATIC Micro Panels
F2
ESC
ENTER
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F1
TOUCH
TD 100C
SIMATIC PANEL
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TD 100C
TD200
F1
F7
F3
F6
F2
F8
F4
SHIFT
ESC ENTER
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F5
TP 177micro
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TD 200 and TD 200C
TD400C
DEL
F10
F2
F11
F3
F12
F4
F13
F5
F14
F6
F15
F7
F16
F8
0
F1
SHIFT
TAB
50
F2
100
F3
F4
INS
HELP
ESC
Tank 3
+/-
ACK
SHIFT ENTER
ESC
ENTER
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F9
F1
ss
Simatic OP 73micro Value 49
OP 73micro
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TD 400C
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Text display TD 100C provides a 4-line display with up to 6
characters per line.
Text displays TD 200 and TD 200C provide a back-lit, highcontrast liquid crystal 2-line display for up to 80 text messages
with integrated variables. TD 200 provides 8 user-configurable
function keys in a fixed arrangement. TD 200C provides up to 20
user-configurable keys in a user-defined layout.
Text Display TD 400C provides a back-lit, high-contrast liquid
crystal 4-line display for up to 80 text messages with integrated
variables.
Graphics operator panel OP 73micro provides a full graphics 3inch display for bitmaps, bars, and text with different font sizes.
Touch Panel TP 177micro provides a 6-inch touch screen for
vector graphics. The graphics on the screen can be set up for
viewing with the panel mounted horizontally or vertically.
30
The SIMATIC S7-200 Programmable Controller System
Manual provides complete information on installing and
programming the S7-200 PLCs. This manual can be downloaded
as a PDF file from the Technical Info link on the Siemens
S7 S00 web site: http://www.automation.siemens.com/_en/s7-200/index.htm
Preface, Contents
2
Installing the S7-200
3
PLC Concepts
4
Programming Concepts,
Conventions and Features
5
S7-200 Instruction Set
6
Communicating over a Network
7
Hardware Troubleshooting Guide
and Software Debugging Tools
Open Loop Motion Control with
the S7-200
Creating a Program for the
Modem Module
Using the USS Protocol Library to
Control a MicroMaster Drive
Using the Modbus Protocol
Library
8
9
10
Using Recipes
13
Using Data Logs
14
PID Auto-Tune and the PID
Tuning Control Panel
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S7-200
Programmable Controller
System Manual
1
Getting Started
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SIMATIC
Product Overview
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Appendices
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Index
1
3
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‑
Reference Manual
11
12
.
The six models of S7-200 are _____ , _____ , _____ ,
_____, _____, and _____ .
1
Which of the following is not available for an CPU 22 ?
2.
a.
b.
c.
d.
Mode Switch
Expansion Module
Programming Port
Status Indicators
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1
Review 3
4.
A CPU 222 DC/DC/DC has ___ DC inputs and ___ DC
outputs without expansion modules.
5.
A CPU 224 DC/DC/DC has ___ DC inputs and ___ DC
outputs without expansion modules.
6.
The fourth output of an S7-200 would be labeled
______ .
7.
S7-200 can be panel mounted or installed on a ______
rail.
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A CPU 222 can have a maximum of___ expansion
modules and a CPU 224 can have a maximum of ___
expansion modules.
3.
32
STEP 7-Micro/WIN is the software used with the S7-200 PLC
to create a user program. STEP 7-Micro/WIN programs consist
of a number of instructions that must be arranged in a logical
order to obtain the desired PLC operation.
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STEP 7-Micro/WIN32
Programming a PLC
Online programming requires the PLC to be connected to
the programming device. In this mode, program changes are
downloaded to the PLC. In addition, status of the input/output
elements can be monitored. The CPU can be started, stopped,
or reset.
33
1
1
11
1
11
‑
S7-200 PLCs have two instruction sets, SIMATIC and
IEC 1131 3. The SIMATIC instruction set was developed by
Siemens prior to the adoption of the IEC 3 -3 standard. The
IEC 3 -3 instruction set was adopted by the International
Electrotechnical Commission (IEC) to provide a common
approach for PLC programming. The IEC 3 -3 instruction set
is often preferred by users who work with PLCs from multiple
suppliers.
11
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STEP 7-MicroWIN programming software can be run off line
or online. Off-line programming allows the user to edit the
program and perform a number of maintenance tasks. The PLC
does not need to be connected to the programming device in
this mode.
PLC ladder logic consists of a commonly used set of symbols
that represent instructions. Understanding these basic symbols
is essential to understanding PLC operation.
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Contacts
Basic Ladder Logic Symbols
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STEP 7-Micro/WIN has three editors for program development,
one for each of the types of programming available, ladder logic
(LAD), statement list (STL), and function block diagram (FBD).
The STL editor is often preferred by experienced programmers
because of the similarity of STL programs to assembly
language computer programs. However, the STL editor can only
be used with the SIMATIC instruction set. Both the LAD and
FBD editors can be used with either instruction set. Throughout
this course, although other instruction types will occasionally be
shown, the emphasis will be on SIMATIC LAD instructions.
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One of the most confusing aspects of PLC programming for
first-time users is the relationship between the device that
controls a status bit and the programming function that uses
a status bit. Two of the most common programming functions
are the normally open (NO) contact and the normally
closed (NC) contact. Symbolically, power flows through these
contacts when they are closed. The normally open contact (NO)
is closed when the input or output status bit controlling the
contact is . The normally closed contact (NC) is closed when
the input or output status bit controlling the contact is 0.
1
Coils represent relays that are energized when power flows
to them. When a coil is energized, it causes a corresponding
output to turn on by changing the state of the status bit
controlling that output to . That same output status bit may be
used to control normally open and normally closed contacts
elsewhere in the program.
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Coils
34
Entering Elements
Control elements are entered in the ladder diagram by
positioning the cursor and selecting the element from a list.
In the following example the cursor has been placed in the
position to the right of I0.2. A coil was selected from a pulldown list and inserted in this position.
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Network 1
I0.1
Q0.0
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Boxes represent various instructions or functions that are
executed when power flows to the box. Typical box functions
include timers, counters, and math operations.
Boxes
Network 2
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I0.2
35
Cursor
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1
1 1
1
Each rung or network on a ladder represents a logic operation.
The following programming example demonstrates an AND
operation. Two contact closures and one output coil are placed
on network . They are assigned addresses I0.0, I0. , and Q0.0.
Note that in the statement list a new logic operation always
begins with a load instruction (LD). In this example I0.0 (input )
and (A in the statement list) I0. (input 2) must be true in order
for output Q0.0 (output ) to be true. This same logic is also
shown in a function block diagram.
1
AND Operation
I0.0
0
0
1
1
I0.1
0
1
0
1
Q0.0
0
0
0
1
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The following truth table represents the state of the output for
each combination of input states.
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1 1
In this example, an OR operation is used in network . In the
following example, if either input I0.2 (input 3) or (O in the
statement list) input I0.3 (input 4), or both are true, then output
Q0. (output 2) is true.
OR Operation
I0.2
0
0
1
1
I0.3
0
1
0
1
Q0 .1
0
1
1
1
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The following truth table represents the state of the output for
each combination of input states.
37
Once a program has been written, it needs to be tested and
debugged. One way this can be done is to simulate the field
inputs with an input simulator, such as the one made for the
S7 200 PLC.
‑
Testing a Program
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The program is first downloaded from the programming device
to the CPU. The selector switch is placed in the RUN position.
The simulator switches are operated and the resulting indication
is observed on the output status indicator lamps.
up
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SF/DIAG
ss
After a program has been loaded and is running in the PLC, the
actual status of ladder elements can be monitored using STEP 7
Micro/WIN software.
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Contact and Coil Status
Input Simulator
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1 1 1 1 1
1 1 1 .s
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For example, in the following illustration, the toggle switch
controls the status bit for I2. . As long as the toggle switch is
open, the I2. status bit is a logic 0. The I2. status bit controls
the I2. normally open contact. Because the I2. status bit is
a logic 0, the normally open contact function is open and no
power is passed to the Q3. coil function. As a result, the Q3.
status bit remains a logic 0 and output point Q3. is off.
CPU Program
Toggle Switch
Input
Point
I2.1
Input
Status Bit
I2.1
OFF
Logic 0
38
I2.1
Q3.1
Output
Status Bit
Q3.1
Output
Point
Q3.1
Logic 0
OFF
Lamp
1 1 1
1 1 1 1 1 1 When the toggle switch closes, input point I2. turns on and
I2. status bit changes to a logic . This causes normally open
contact I2. to close and turn on Q3. coil. Note that a closed
contact and a coil that is on are shown highlighted in the
program. When Q3. coil turns on, the Q3. status bit goes to a
logic and output point Q3. turns on. This causes the lamp to
light.
ON
Logic 1
Q3.1
Output
Status Bit
Q3.1
Output
Point
Q3.1
Lamp
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Input
Status Bit
I2.1
Logic 1
ON
Forcing is another useful tool in the startup and maintenance
of a PLC system. Forcing overrides one or more input or output
status bits, causing them to stay in either a logic 0 or logic
status.
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Forcing
Input
Point
I2.1
I2.1
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CPU Program
Toggle Switch
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1 1 1
1 en
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For example, in the following illustration, the toggle switch is
open. Under normal circumstances, the toggle switch would
have to be closed to turn on the lamp. However, if the I2.
status bit is forced to a logic , the lamp will turn on, as long as
the program is functioning correctly and there are no hardware
or wiring problems. Similarly, the Q3. status bit could be forced
to a logic to turn on the lamp.
Input
Point
I2.1
Input
Status Bit
I2.1
OFF
Logic 0
Toggle Switch
Q3.1
Output
Status Bit
Q3.1
Output
Point
Q3.1
Logic 0
OFF
Output
Status Bit
Q3.1
Output
Point
Q3.1
Logic 1
ON
Lamp
CPU Program
Input
Point
I2.1
Input
Status Bit
I2.1
OFF
Logic 1
I2.1
Q3.1
Lamp
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.s
Toggle Switch
CPU Program
I2.1
Forcing is useful not only to test and debug programs and
hardware during startup, but also to troubleshoot systems with
problems.
39
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The following table shows the appearance of ladder diagram
elements with associated status bits in the on, off, forced on,
and forced off conditions.
40
While the lamp application previously discussed is useful to
explain basic PLC operation, a more practical, and only slightly
more complex, application is start-stop control of an AC motor.
Before examining the PLC application, first consider a hardwired approach.
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Motor Starter Example
Discrete Inputs/Outputs
Frame-EG
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The following line diagram illustrates how a normally open and
a normally closed pushbutton might be connected to control
a three-phase AC motor. In this example, a motor starter coil
(M) is wired in series with a normally open, momentary Start
pushbutton, a normally closed, momentary Stop pushbutton,
and normally closed overload relay (OL) contacts.
Type/Tipo NEG
100 Amp
O
N
O
100
en
O
F
F
l
Contactor
Circuit Breaker
Overload Relay
M
OL
M
OL
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L1
L2
M
OL
Stop Pushbutton
Motor
T3
Start Pushbutton
OL
Starter Coil
Ma
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Auxiliary Contact
(Holding Circuit)
Momentarily pressing the Start pushbutton completes the path
for current flow and energizes the motor starter (M). This closes
the associated M and Ma (auxiliary contact located in the motor
starter) contacts. When the Start button is released, current
continues to flow through the Stop button and the Ma contact,
and the M coil remains energized.
4
1
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T2
M
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L3
T1
This motor control application can also be accomplished
with a PLC. In the following example, a normally open Start
pushbutton is wired to the first input (I0.0), a normally closed
Stop pushbutton is wired to the second input (I0. ), and
normally closed overload relay contacts (part of the motor
starter) are connected to the third input (I0.2). These inputs are
used to control normally open contacts in a line of ladder logic
programmed into the PLC.
Input
Points
I0.0
Stop (NC)
CPU Program
up
Start (NO)
pl
SF/DIAG
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PLC Motor Control
The motor will run until the normally closed Stop button
is pressed, unless the overload relay (OL) contacts open.
When the Stop button is pressed, the path for current flow is
interrupted, opening the associated M and Ma contacts, and
the motor stops.
Network 1
I0.0 I0.1 I0.2
Q0.0
Q0.0
Motor
Starter
Motor
ss
I0.1
Output
Point
Q0.0
OL
en
I0.2
1 1 1 Normally open output Q0.0 contact is also programmed on
Network as a sealing contact. With this simple network,
energizing output coil Q0.0 is required to turn on the motor.
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1 Initially, I0. status bit is a logic because the normally closed
(NC) Stop Pushbutton is closed. I0.2 status bit is a logic
because the normally closed (NC) overload relay (OL) contacts
are closed. I0.0 status bit is a logic 0, however, because the
normally open Start pushbutton has not been pressed.
42
When the Start pushbutton is pressed, the CPU receives a logic
from input I0.0. This causes the I0.0 contact to close. All three
inputs are now a logic . The CPU sends a logic to output
Q0.0. The motor starter is energized and the motor starts.
Start (NO)
Input
Points
I0.0
Stop (NC)
1 1
1 Program Operation
CPU Program
Output
Point
Network 1
I0.0 I0.1 I0.2
Motor
Starts
Q0.0
Q0.0
Motor
Starter
Q0.0
OL
Motor
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I0.1
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I0.2
Start (NO)
Input
Points
I0.0
CPU Program
Output
Point
Network 1
I0.0 I0.1 I0.2
Q0.0
Motor is
Running
Q0.0
Motor
Starter
ss
Stop (NC)
up
pl
1
The output status bit for Q0.0 is now a . On the next scan,
when normally open contact Q0.0 is solved, the contact will
close and output Q0.0 will stay on even if the Start pushbutton
is released.
I0.1
Motor
Q0.0
OL
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I0.2
Start (NO)
1 1 Input
Points
I0.0
Stop (NC)
CPU Program
I0.0 I0.1 I0.2
I0.1
Q0.0
OL
Output
Point
Network 1
I0.2
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When the Stop pushbutton is pressed, input I0. turns off,
the I0. contact opens, output coil Q0.0 de-energizes, and the
motor turns off.
43
Q0.0
Motor
Stops
Q0.0
Motor
Starter
Motor
The application can be easily expanded to include indicator
lights for run and stop conditions. In this example, a RUN
indicator light is connected to output Q0. and a STOP indicator
light is connected to output Q0.2.
1 Adding Run and Stop
Indicator Lights
Input
Points
I0.0
Stop (NC)
CPU Program
Network 1
I0.0 I0.1 I0.2
I0.1
Q0.0
I0.2
Network 2
Q0.0
Q0.0
Q0.0
Motor
Starter
up
OL
Output
Points
pl
Start (NO)
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1 The ladder logic for this application includes normally open
Q0.0 contact connected on Network 2 to output coil Q0.
and normally closed Q0.0 contact connected on Network 3
to output coil Q0.2. When Q0.0 is off, the normally open Q0.0
contact on Network 2 is open and the RUN indicator off. At the
same time, the normally closed Q0.0 contact is closed and the
STOP indicator is on.
Motor
Q0.1
Q0.1
RUN Indicator
Q0.2
STOP Indicator
Q0.2
en
ss
Network 3
Q0.0
Motor is
Stopped
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When the Start button is pressed, the PLC starts the motor.
Output Q0.0 is now on. Normally open Q0.0 contact on
Network 2 is now closed and the RUN indicator is on. At the
same time, the normally closed Q0.0 contact on Network 3 is
open and the STOP indicator light connected to output Q0.2 is
off.
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Start (NO)
Input
Points
I0.0
Stop (NC)
CPU Program
Output
Points
Network 1
I0.0 I0.1 I0.2
Q0.0
Motor is
Running
Q0.0
Motor
Starter
I0.1
Motor
Q0.0
OL
I0.2
Network 2
Q0.0
Network 3
Q0.0
44
Q0.1
Q0.1
RUN Indicator
Q0.2
STOP Indicator
Q0.2
The application can be further expanded by adding a limit
switch. The limit switch could be used in this application for a
variety of functions. For example, the limit switch could be used
to stop the motor or prevent the motor from being started.
Adding a Limit Switch
Start (NO)
Input
Points
I0.0
Stop (NC)
CPU Program
Output
Points
Network 1
I0.0 I0.1 I0.2 I0.3
Q0.0
Network 3
Q0.0
Q0.1
Q0.1
RUN Indicator
Q0.2
STOP Indicator
up
I0.3
With I0.3 Contact Open,
Motor will not Start
Q0.2
ss
Access Door
Open
LS1
Network 2
Q0.0
Motor is
Stopped
Motor
pl
Q0.0
I0.2
Q0.0
Motor
Starter
I0.1
OL
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1 In this example, the limit switch is associated with an access
door to the motor or its associated equipment. The limit switch
is connected to input I0.3 and controls a normally open contact
in the program. If the access door is open, limit switch LS is
open and normally open contact I0.3 is also open. This prevents
the motor from starting.
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Start (NO)
Input
Points
I0.0
Stop (NC)
1 en
When the access door is closed, limit switch LS is closed and
normally open contact I0.3 is also closed. This allows the motor
to start when the Start pushbutton is pressed.
CPU Program
Output
Points
Network 1
I0.0 I0.1 I0.2 I0.3
Q0.0
Motor
Starter
.s
I0.1
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OL
LS1
Q0.0
Motor
With I0.3 Contact Closed,
Motor can be Started
Network 2
Q0.0
Q0.1
I0.3
Network 3
Q0.0
Q0.1
RUN Indicator
Q0.2
STOP Indicator
Q0.2
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Access Door
Closed
I0.2
Motor is
Stopped
Q0.0
45
Further Expansion
The PLC program can be further expanded to accommodate a
wide variety of commercial and industrial applications.
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Start/Stop pushbuttons, selector switches, indicator lights, and
signaling columns can be added. Motor starters can be added
for control of additional motors. Over-travel limit switches can
be added along with proximity switches for sensing object
position. Various types of relays can be added to expand the
variety of devices being controlled.
Signaling
Column
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Indicator Lights
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As needed, expansion modules can be added to further
increase the I/O capability. The applications are only limited by
the number of I/Os and amount of memory available for the
PLC.
Relays
Motor Starters
Discrete Ouputs
SF/DIAG
Expansion Module
Selector
Switch
Pushbuttons
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Discrete Inputs
46
Limit Switches
Proximity Switches
.
Identify the following symbols:
1
Review 4
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a. ____________
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b. ____________
c. ____________
Complete the following tables:
pl
2.
AND Function
Input 1
Input 2
Output
0
1
0
1
a. ___
b. ___
c. ___
d. ___
0
0
1
1
0
1
0
1
e. ___
f. ___
g. ___
h. ___
In the following network, coil Q0.0 will be on when
contact ____ is closed and either contact ____ or
contact ____ or both are closed.
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3.
Output
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0
0
1
1
Input 2
up
Input 1
OR Function
47
Analog Inputs and Outputs
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Many PLCs also work with analog I/O devices. Analog devices
use signals that are continuously variable within a specified
range, such as 0 to 0 VDC or 4 to 20 mA.
pl
1
Analog signals are used to represent variable values, such as
speed, rate of flow, temperature, weight, level, etc. In order to
process an input of this type, a PLC must convert the analog
signal to a digital value. S7-200 PLCs convert each analog
voltage or current value into a 2-bit digital value.
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Digital values from analog inputs are stored in addressable
memory for use by the user program. Similarly, the user
program can place digital values in addressable memory
locations for conversion to analog values for the designated
analog outputs.
1 1
1 Expansion modules are available with 4 or 8 analog inputs,
2 or 4 analog outputs, or 4 analog inputs and analog
output. In addition, expansion modules are available for use
with thermocouples or RTD type sensors which sense the
temperature at a specific point in a machine or process.
SF/DIAG
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The only S7-200 CPU model with analog I/O points on board
is CPU 224XP, which has 2 analog inputs and analog output.
However, analog I/O points can be added using expansion
modules for any CPU other than CPU 22 . CPU 222 allows
for 2 expansion modules and the remaining CPUs allow for 7
expansion modules.
Analog Expansion Module
48
Analog Input Example
Analog inputs can be used for a variety of purposes. In the
following example, a scale is connected to a load cell. A load
cell is a device that generates an electrical output proportional
to the force applied.
Package Route
Controled by PLC
Scale
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Inspection
Station
0 to 10 VDC Analog Signal to PLC
Desired Weight = 25 LBS = 5 VDC
Finished
Goods
Inventory
1
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The load cell in this example converts a value of weight from 0
to 50 pounds into a 0 - 0 VDC analog value. The 0 - 0 VDC load
cell signal is connected to an S7-200 PLC’s analog input.
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The analog value applied to the PLC can be used in various
ways. For instance, the actual weight can be compared to a
desired weight for a package. Then, as the package is moved
on a conveyor, the S7-200 PLC can control a gate to direct
packages of varying weight.
49
Analog Output Example
Analog outputs from a PLC are often supplied directly or
through signal converters or transmitters to control valves,
instruments, electronic drives or other control devices which
respond to analog signals.
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For example, analog outputs from the PLC could be used to
control the flow of fluid in a process by controlling AC drives.
Rather than simply turning the AC drives on or off, which could
be accomplished by discrete outputs, analog signals can be
used to control the output of the AC drives. This would allow
the speed of the pumps to be varied dynamically in response to
changes in process requirements.
AC Drives
PLC
Level
Transmitter
Storage
Tank
Pump 1
Pump 2
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Process
50
To Pump 1
Analog
Outputs
pl
Analog
Input
up
Signal from
Level Transmitter
Central
Processing
Unit
(CPU)
To Pump 2
Timers
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1 1 pl
1 1 1
Timers in a PLC program can be compared to hard-wired timing
circuits, such as the one represented in the accompanying
control line diagram. In this example, normally open (NO) switch
(S ) is used with timer (TR ). When S closes, TR begins
timing. When the timer’s preset time elapses, TR closes its
associated normally open TR contact and pilot light PL turns
on. When S opens, TR de-energizes immediately, the TR
contact opens, and PL turns off.
1
Hard-wired Timing Circuit
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In a PLC, timers are programming functions that keep track
of time and allow PLC programs to provide varied responses
depending on the elapsed time.
ss
TR1
S1
TR1
S1
PL1
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PL1
TR1
Closes a preset time
after S1 closes
1 This type of timer is referred to as an on-delay timer. The term
“on-delay” indicates that the timing begins when the timer
receives a signal to turn on. In this example, that happens when
S closes.
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TR1
1
5
The S7-200 SIMATIC LAD instruction set includes three types
of timers: On-Delay Timer (TON), Retentive On-Delay Timer
(TONR), and Off-Delay Timer (TOF). Timers are represented in an
S7-PLC ladder logic program by boxes.
S7-200 SIMATIC Timers
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1
1
1 S7-200 timers have a resolution of millisecond,
0 milliseconds, or 00 milliseconds. This resolution appears
in the lower right corner of the timer box. As shown in the
following illustration, the resolution and type of timer that can
be used depends on the timer number. The maximum value of
time shown is for a single timer. By adding program elements,
greater time intervals can be timed.
SIMATIC Timers
Timer Number (T0 to T255)
Txxx
TON
PT
xxx ms
IN
up
IN
pl
Txxx
On-Delay Timer
PT
Txxx
TONR
IN
TOF
xxx ms
PT
xxx ms
Retentive On-Delay Timer
Off-Delay Timer
ss
Timer Resolution
1 ms, 10 ms, or 100 ms
en
Timer Type
TONR
(retentive)
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Maximum Value
32.767 seconds
327.67 seconds
3276.7 seconds
32.767 seconds
327.67 seconds
3276.7 seconds
The previous example illustrated how a hardware on-delay timer
works. The corresponding software function in the S7-200
SIMATIC LAD instruction set is the On-Delay Timer (TON).
After the On-Delay Timer (TON) receives an enable (logic ) at
its input (IN), a predetermined amount of time (preset time - PT)
passes before the timer bit (T-bit) turns on. The T-bit is a logic
function internal to the timer and is not shown on the symbol.
The timer resets the accumulated time to zero when the
enabling input goes to a logic 0.
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SIMATIC On-Delay Timer
(TON)
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TON, TOF
(non-retentive)
Timer Number
Resolution
T0, T64
1 ms
T1 to T4, T65 to T68
10 ms
T5 to T31, T69 to T95
100 ms
T32, T96
1 ms
T33 to T36, T97 to T100
10 ms
T37 to T63, T101 to T255
100 ms
52
1 1
1
1
1
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1 1
1
1
1
1
In the following timer example, when input I0.3 turns on, the
I0.3 contact closes, and timer T37 begins timing. T37 has a time
base of 00 ms (0. seconds). The preset time (PT) value has
been set to 50. Because the resolution of the timer is set to
00 ms, a preset value of 50 is equal to 5 seconds ( 50 x 00
ms). Therefore, 5 seconds after the I0.3 contact closes, timer
bit T37 becomes a logic , the T37 contact closes, and output
coil Q0. and its associated output point turn on.
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If the switch opens before 5 seconds has elapsed, the
accumulate time resets to 0. Because this type of timer does
not retain its accumulated time when its input (IN) goes to logic
0, it is said to be non-retentive.
Network 1
I0.3
T37
TON
PT
100 ms
pl
IN
up
+150
Preset time = 150 x 100 ms = 15 seconds
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Network 2
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T37
53
Q0.1
SIMATIC Retentive On-Delay The SIMATIC Retentive On-Delay Timer (TONR) functions in
Timer (TONR)
a similar manner to the On-Delay Timer (TON). Just like the OnDelay timer (TON), the Retentive On-Delay Timer (TONR) times
when the enabling input (IN) is on. However, the Retentive OnDelay Timer (TONR) does not reset when the input (IN) turns off.
Instead, the timer must be reset with a Reset (R) instruction.
1
1
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1
1
The following example shows a Retentive On-Delay timer
(TONR) with a resolution of 00 ms and preset value of 50 ( 5
seconds). When input I0.3 turns on, I0.3 contact closes, and
timer T5 begins timing. If, for example, after 0 seconds input
I0.3 turns off, the timer stops. When input I0.3 turns on again,
the timer begins timing at 0 seconds. Timer bit T5 turns on 5
seconds after input I0.3 closes for the second time. When timer
bit T5 turns on, contact T5 closes, and output Q0. turns on.
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1
The Reset (R) function, shown in network , is necessary to
reset the accumulated time of the Retentive On-delay Timer
(TONR) to zero. In this example, the Reset (R) function turns on
and resets the timer when contact I0.2 closes. This causes the
T5 contact to open and output Q0. to turn off.
Network 1
T5
I0.2
en
R
Network 2
T5
+150
IN
TONR
PT
100 ms
Network 3
Q0.1
T5
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I0.3
54
The SIMATIC Off-Delay Timer (TOF) begins timing when input
(IN) turns off. In the following example, when contact I .4
closes, the current value of timer T33 is set to 0, timer bit T33
turns on immediately, closing the T33 contact, and turning on
output Q2.3.
1
SIMATIC Off-Delay Timer
(TOF)
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1
When contact I .4 opens, the timer times until the preset time
elapses, 200 ms in this example. Then, timer bit T33 turns off,
contact T33 opens, and output Q2.3 turns off.
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If the I .4 contact had closed again before the 200 ms preset
time had elapsed, the timer’s current value would again be set
to 0, timer bit T33 would remain on, contact T33 would remain
closed, and output Q2.3 would remain on.
Network 1
up
pl
I1.4
ss
+20
T33
IN
TOF
PT
10 ms
Preset time = 20 x 10 ms = 200 ms
Network 2
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T33
55
Q2.3
11
1
It is not the intent of this course to cover all S7-200 instructions,
but timer instructions provide an opportunity to understand
some of the differences between the SIMATIC and IEC 3 -3
instruction sets.
IEC 1131-3 Timers
1
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1
1 ‑
The timers previously discussed were SIMATIC timers.
The IEC 1131-3 instruction set also includes three timers,
On Delay Timer (TON), Off-Delay Timer (TOF), and Pulse
Timer (TP). The same three resolutions ( ms, 0, ms, and 00
ms) are available as for the SIMATIC timers, and the resolution
is determined by the timer number as shown in the following
illustration.
IEC 1131-3 Timers
Timer Number (T0 to T255)
TON
PT
xxx ms
Q
IN
PT
xxx ms
up
IN
%Txxx
ET
Elapsed
Time
TOF
Q
ET
Off-Delay Timer
IN
TP
PT
xxx ms
ET
Q
Pulse Timer
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On-Delay Timer
Resolution
(1 ms, 10 ms, 100 ms)
%Txxx
pl
%Txxx
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Timer Number
Resolution Maximum Value
T32, T96
1 ms
32.767 seconds
T33 to T36, T97 to T100
10 ms
327.67 seconds
T37 to T63, T101 to T255 100 ms 3276.7 seconds
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The On-Delay Timer (TON) begins timing when its enable input
(IN) turns on. When the elapsed time (ET) equals the preset
time (PT), the timer stops timing, and the output (Q) turns on.
The timer is reset, when IN turns off.
The Off-Delay Timer (TOF) output (Q) turns on immediately
when IN turns on. When IN turns off, the timer begins timing.
When ET equals PT, Q turns off. The elapsed time is maintained
until the next time IN turns on. If IN turns on before ET equals
PT, Q remains on.
The Pulse Timer (TP) generates pulses of a preset duration.
When IN turns on, Q turns on, and the timer begins timing.
When ET equals PT, Q turns off. The elapsed time is maintained
until IN turns off.
56
.
CPU ________ has two analog inputs and one analog
output on-board.
1
Review 5
3.
The maximum time value for a 00 millisecond time
base timer is ____________ seconds.
4.
Which SIMATIC Timer requires a Reset instruction?
5.
Three types of IEC 3 -3 timers available in the S7-200
instruction set are _____________, _____________, and
_____________.
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1
11
1
Three types of SIMATIC timers available in the S7-200
instruction set are _____________, _____________, and
_____________.
2.
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Counters
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The S7-200 SIMATIC LAD instruction set includes three types
of counters: Count Up Counter (CTU), Count Down Counter
(CTD), and Count Up/Down Counter (CTUD).
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S7-200 SIMATIC Counters
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Just like mechanical counters, PLC counter instructions keep
track of events. As it counts, a counter instruction compares an
accumulated count value to a preset value to determine when
the desired count has been reached. Counters can be used to
start an operation when a count is reached or to prevent an
operation from occurring until a count has been reached.
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SIMATIC Counters
Timer Number (C0 to C255)
CU
CD
CTU
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R
Cxxx
ss
Cxxx
PV
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Count Up Counter
CTD
LD
PV
Count Down Counter
Cxxx
CU
CTUD
CD
R
PV
Count Up/Down Counter
The Count Up Counter (CTU) counts up by one each time
the count up (CU) input transitions from off to on. When the
accumulated count equals the preset value (PV) the counter
bit (not shown) turns on. The counter continues to count until
the accumulated count equals the maximum value (32767).
When the reset input (R) turns on or when a Reset instruction is
executed, the accumulated count resets to zero and the counter
bit turns off.
The Count Down Counter (CTD) counts down by one each
time the count down (CD) input transitions from off to on. When
the count reaches zero, the counter bit turns on. When the
load (LD) input turns on, the counter resets the current value to
equal the preset value (PV), and the counter bit turns off.
58
The Count Up/Down Counter (CTUD) counts up by one each
time the count up (CU) input transitions from off to on and
counts down by one each time the count down (CD) input
transitions from off to on. When the accumulated count equals
the preset value (PV), the counter bit turns on. When the reset
input (R) turns on or when a Reset instruction is executed, the
accumulated count resets to zero and the counter bit turns off.
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Counters are common instructions used for counting a wide
variety of events such as parts manufactured or packed, items
processed, machine operations, etc. For example, a counter
might be used to keep track of the items in an inventory
storage area.
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Count Up/Down Counter
(CTUD) Example
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If the count reaches the maximum positive value (32,767),
the next count up input sets the accumulated count to the
maximum negative value (-32,767). Similarly, if the count
reaches the maximum negative value, the next down count
sets the accumulated count to the maximum positive value.
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In the following example, Count Up/down Counter (CTUD) C48
is reset to zero when contact I0.2 closes. This could be event
could be triggered automatically or manually to indicate that the
associated storage location is empty.
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When contact I0.0 closes, the counter counts up by . This
could be triggered by a proximity switch sensing that an item
has been placed in the storage location.
1
1 When contact I0. closes, the counter counts down by . This
could be triggered by a proximity switch sensing that an item
has been removed from the storage location.
C48
CU
CTUD
I0.1
CD
I0.2
R
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I0.0
+150
C48
PV
Q0.1
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1
The counters previously discussed were SIMATIC counters. The
IEC 3 -3 instruction set also includes three counters. These
counters are similar to the SIMATIC counters, but there are a
few differences.
11
IEC 1131-3 Counters
1 1
1
In this example, the storage location has 50 spaces. When
the accumulated count reaches 50, the counter bit turns
on, contact C48 closes, and output Q0. turns on. This could
trigger other logic in the program to divert new items to
another location until such time as an item is removed from this
location.
1
11
Each IEC 3 -3 counter has an output (Q) and cumulative value
(CV) in the counter box.
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Count Up Counter (CTU) stops counting when CV equals the
preset value (PV), and turns on output Q.
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Except for the CV and Q values, the IEC 3 -3 Count Down
Counter (CTD) functions like the SIMATIC version. When CV
equals zero, it stops counting, and output Q turns on.
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Count Up/Down Counter (CTUD) stops counting up when CV
equals PV and turns on output QU. CTUD stops counting down
when CV equals zero and turns on output QD.
IEC 1131-3 Counters
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Timer Number (C0 to C255)
CU
Cxxx
Cxxx
CD
CTU
.s
CTUD
R
LD
Q
PV
CV
LD
Q
CV
Count Up Counter
Count Down Counter
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CU
CD
R
PV
Cxxx
CTD
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PV
QU
QD
CV
Count Up/Down Counter
High-Speed Instructions
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Inp
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As discussed earlier, PLCs have a scan time. The scan time
depends on the size of the program, the number of I/Os, and
the amount of communication required. However, events may
occur in an application that require a response from the PLC
sooner than the scan cycle would normally permit. For these
applications high-speed instructions, such as those associated
with high-speed counters, can be used.
PLC Scan
O
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Upd
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Di mu
Com
A high-speed counter is represented by two boxes in ladder
logic. One box is the High-Speed Counter Definition (HDEF)
instruction and the other box is the High-Speed Counter
(HSC) instruction.
1
1 CPU 22 and CPU 222 support four high-speed counters
(HSC0, HSC3, HSC4, HSC5). CPU 224, CPU 224XP, CPU
224XPsi, and CPU 226 support six high-speed counters (HSC0,
HSC , HSC2, HSC3, HSC4, HSC5).
HDEF
EN
HSC
ENO
HSC
EN
ENO
N
MODE
High-Speed Counter Definition
6
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High-Speed Counters
ts
High-Speed Counter
The High-Speed Counter Definition (HDEF) instruction assigns
the operating mode to a specific high-speed counter (HSCx).
The mode selection defines the clock, direction, start, and
reset functions of the high-speed counter. High-speed counters
can be defined by the definition box to operate in any of the
2 available modes. Not all counters can operate in all of the
available modes, however. Refer to the S7-200 System Manual
for definitions available for each counter.
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Definition Boxes and
High-Speed Counters
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Positioning is one example of an application that may require
use of a high-speed counter. In the following illustration, two
PLC discrete outputs (one for forward and one for reverse)
control a reversing motor starter, which, in turn, controls a
motor.
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Positioning Example
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The High-Speed Counter (HSC) instruction configures and
controls a specific high-speed counter based upon the state of
the special HSC bits. The N parameter specifies the high-speed
counter number. Each counter has dedicated inputs for clocks,
direction control, reset, and start, where these functions are
supported.
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The motor shaft is connected to an encoder and to a positioning
screw. A platform mounted on the positioning screw moves
away from position 0 as the motor turns in the forward direction
and towards position 0 as the motor turns in the reverse
direction. Pulses from the encoder are connected to PLC inputs
associated with a high speed counter.
1
2
3
4
5
6
7
8
9 10
Motor
Reversing
Motor Starter
SF/DIAG
B0
B23-0X
212-1B
1 In this example, the high-speed counter is programmed to
move the platform from position to position 6 and later to
return to position . These positions could be associated with
manufacturing operations performed on a part mounted on the
platform.
1
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Encoder
0
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S7-200 PLCs incorporate instructions for use with interrupts.
Interrupts are used to initiate a specific, short PLC program
segment, called an interrupt routine, when an internal or
external event occurs. After the interrupt routine has been
executed, control is returned to the main program.
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Interrupts
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1 1
Assume, for example, that the encoder generates 600 pulses
per revolution, and it takes 000 motor revolutions to move
the platform from one position to another, moving the platform
from position to position 6 (5 positions) takes 5000 motor
revolutions or 30,000 encoder pulses. In most practical
applications, the frequency of these pulses is too high for them
to be counted with inputs that are not associated with a highspeed counter.
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Three types of interrupts are supported by S7-200 PLCs,
communication port interrupts, I/O interrupts, and timebased interrupts. Communication port interrupts are used
to control a communication port operated in Freeport mode.
I/O interrupts are used to respond quickly to high-speed I/O
transitions, such as those associated with high-speed counters
or pulse train outputs. Time-based interrupts allow the user
program to execute an interrupt routine on a cyclic basis.
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S7-200 PLCs have two PTO/PWM generators that create either
a high-speed pulse train or a pulse width modulated waveform.
One generator is assigned to output point Q0.0 and the other to
output point Q0. . When a generator is activated, it controls its
respective output.
Pulse Train Output (PTO) is used to provide a series of pulses
to an output device, such as a stepper motor driver. The PTO
provides a square wave output for a specified number of pulses
and a specified cycle time. The number of pulses can be from
to 4,294,967,295 pulses. The Pulse Train Output has a 50% duty
cycle. This means the pulse is off for the same amount of time
that it is on.
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Pulse Training Output (PTO)
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Each of these types of interrupts has an associated priority
that determines which interrupt is processed first in the event
that two or more interrupts are requested at the same time.
Communication port interrupts have the highest priority and
time-based interrupts have the lowest priority.
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1 1 The number of pulses and the cycle time can be changed with
an interrupt. In the accompanying example, each pulse is initially
on for 500 ms and off for 500 ms. After four pulses, an interrupt
occurs which changes the cycle time to 2 seconds, second on
and second off.
1 sec 1 sec
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The Pulse Width Modulation (PWM) function provides a
fixed cycle time with a variable duty cycle. When the pulse
width is equal to the cycle time, the duty cycle is 00% and the
output is turned on continuously. In the following example, the
output initially has a 0% duty cycle (on 0%, off 90%). After an
interrupt, the output switches to a 50% duty cycle (on 50%, off
50%).
Off
On
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Off
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On
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Pulse Width Modulation
(PWM)
500 ms
Interrupt
Occurs
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10% Duty Cycle
50% Duty Cycle
Interrupt
Occurs
‑
The instructions listed in this section are only examples of
the types of instructions available for S7-200 PLCs. The full
instruction set includes a much broader range of capabilities.
Refer to the S7 200 System Manual for additional information.
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And Much More
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The PWM function can be used to provide a programmable
or adjustable control of machine timing. This allows machine
operation to be varied to compensate for product variations or
mechanical wear.
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Specialized Expansion Modules
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In addition to the expansion modules previously discussed
that provide additional discrete or analog I/O, several expansion
modules are available to provide communication interfaces or
specialized I/O functions.
EM 241 Modem Module
SF/DIAG
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EM 241
MODEM
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One of these modules is the EM 241 Modem module. This
module supports communication between a computer with
STEP 7 Micro/WIN and an S7-200 PLC.
241-1AA22-0XA0
Modem
Computer
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S7-200 PLC with
EM 241 Modem Module
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1 The EM 24 provides an international telephone line interface
and supports sending numeric and text paging messages, as
well as SMS (Short Message Service) messages to cellular
phones. This is useful for remote diagnostics and maintenance,
machine control, alarm systems, and general communication
functions.
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SINAUT MD 720-3
GSM/GPRS Modem Module
1 In addition to CPU-to-CPU communication via a telephone line,
the EM 24 also supports Modbus RTU protocol, a protocol
that has been widely used for many years.
SINAUT Telecontrol (Siemens Network Automation) permits
networking of individual controls and control systems over a
WAN (Wide Area Network).
One approach for providing this capability is SINAUT Micro.
This is a simple and flexible way to link stationary or mobile
stations to a master control center. SINAUT Micro is appropriate
where smaller amounts of data have to be transmitted to
permit monitoring and control of remote stations using wireless
techniques with the General Packet Radio Service (GPRS) of the
Global System for Mobile Communication (GSM) mobile radio
network.
65
The SINAUT MD720-3 GSM/GPRS Modem module and
associated ANT794-4MR antenna are the hardware elements
used to connect an S7-200 PLC into a SINAUT Micro system.
SINAUT Micro SC software is also required.
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WinCC flexiible,
WinCC
SET
X1
SINAUT
MD720-3
720-3AA00
Antenna
Industrial Ethernet provides a proven means of networking
computers and a variety of intelligent devices. CP 243-1 and CP
243-1 IT communication processors are used to connect an
S7-200 PLC to an Industrial Ethernet network.
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CP 243-1, CP 243-1 IT
Communication Processors
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SINAUT MD 720-3
GSM/GPRS Modem Module
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RS232
S O C
1 1 The IT functions of the CP 243- IT Internet module simplify the
process of setting up a control system that can email diagnostic
information or transfer files using Internet protocols.
S7-200 PLC with
CP 243-1 or CP 243-1 IT
Communication Processor
SF/DIAG
SIMATIC S7-300 PLC
CP 243-1
Ethernet CP
243-1EX00-0XE0
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1 CP 243- and CP 243- IT communication processors can be
used to connect an S7-200 PLC via Industrial Ethernet to a
computer running STEP 7 Micro/WIN. This allows the S7-200
PLC to be configured, programmed, and diagnosed remotely.
In addition, an S7-200 PLC connected to an Industrial Ethernet
network can communicate with S7-200, S7-300, and S7-400
PLCs and a variety of other devices.
Industrial Ethernet
Programming Device (PG)
or Computer
66
SIMATIC S7-400 PLC
PROFIBUS DP is an open, international fieldbus communication
standard that allows a broad range of intelligent devices from
various manufacturers to communicate rapidly and efficiently.
This reduces wiring costs as well as start-up and maintenance
expenses.
EM 277 PROFIBUS-DP
Module
Other SIMATIC
Controllers
8
2
0
SIMATIC
S7 - 200
6
X10
4
8
CPU 224
AC/DC/RLY
01
00
.0 .1 .2 .3 .4 .5 .6 .7
.0 .1
6
2
0
SF/DIAG
RUN
STOP
X1
EM 277
PROFIBUS-DP
4
CPU FAULT
POWER
DP ERROR
DX MODE
I0
.0 .1 .2 .3 .4 .5 .6 .7
I1
Other Intelligent
Devices and Systems
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S7-200 PLC with
EM 277 PROFIBUS DP Module
Non-Siemens
Controllers
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EM 277 PROFIBUS-DP module allows connection of the
S7 200 CPU (CPU 222 and above) to a PROFIBUS-DP network
as a slave.
.0 .1 .2 .3 .4 .5
PORT
0
Computers
Actuator Sensor Interface (AS-Interface or AS-i) is a system
for networking field devices such as sensors and actuators
with control and operator interface devices. AS-i replaces the
extensive parallel wiring often used to connect sensors and
actuators to controllers with a simple 2-core cable. The cable is
designed so that devices can only be connected correctly.
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CP 243-2 AS-Interface
Master Module
Display Systems
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I/O Systems
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PROFIBUS DP
.s
CP 243-2 AS-Interface Master module allows connection of
the S7-200 CPU (CPU 222 and above) to a AS-I network as a
master.
SIMATIC
S7 - 200
SF/DIAG
RUN
STOP
01
00
.0 .1 .2 .3 .4 .5 .6 .7
.0 .1
CPU 224
AC/DC/RLY
CM
APF
SF
CP 243-2
AS-Interface Master
SET
CER PWR
AUP
0 1 2 3
B
4
5 6 7 8 9
10 11 12 13 14
15 16 17 18 19
20 21 22 23 24
I0
.0 .1 .2 .3 .4 .5 .6 .7
I1
25 26 27 28 29
30
31 31
.0 .1 .2 .3 .4 .5
DISPLAY
6GK7 243-2AX01-0XA0
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AS-Interface
Power Supply
PORT
0
Slaves
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S7-200 PLC with
CP 243-2 AS-Interface
Master Module
AS-Interface
Power Supply
Repeater
100 meters
S7-200 PLC with
CP 243-2 AS-Interface
Master Module
SIMATIC
S7 - 200
SF/DIAG
RUN
STOP
00
01
.0 .1 .2 .3 .4 .5 .6 .7
.0 .1
CPU 224
AC/DC/RLY
CM
APF
SF
CP 243-2
AS-Interface Master
SET
CER PWR
AUP
0 1 2 3
B
4
5 6 7 8 9
10 11 12 13 14
15 16 17 18 19
Slaves
100 meters
AS-Interface
Extension Plug
AS-Interface
Power Supply
20 21 22 23 24
I0
.0 .1 .2 .3 .4 .5 .6 .7
I1
.0 .1 .2 .3 .4 .5
25 26 27 28 29
30
31 31
DISPLAY
6GK7 243-2AX01-0XA0
PORT
0
Slaves
Slaves
200 meters
67
SF/DIAG
MF
EM 253
Position
MG
P0
DIS
P1
CLR
PWR
STP
ZP LMT
RPS
- +
253-1AA22-0XA0
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Features of the module include:
•
•
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•
•
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•
68
Provides high-speed control with a range from 20 to
200,000 pulse per second
Supports both S curve or linear acceleration and
deceleration
Provides a configurable measuring system that allows
you to enter data as engineering units (such as inches or
centimeters) or as a number of pulses
Provides configurable backlash compensation
Supports absolute, relative, and manual methods of
position control
Provides continuous operation
Provides up to 25 motion profiles with up to 4 speed
changes per profile
Provides four different reference-point seek modes with
a choice of the starting seek direction and final approach
direction for each sequence
Provides removable field wiring connectors for easy
installation and removal
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S7-200 PLC with EM 253 Position Module
EM 253 Features
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Position control describes a range of applications that involve
movement with varying degrees of precision. The EM 253
Position module is a simple but powerful positioning module
that enables the user to control position systems from microsteppers to intelligent servo drives (with integrated closed-loop
control).
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EM 253 Position Module
Expansion Modules for
Temperature Measurement
Two S7-200 PLC expansion modules are available for accurate
temperature measurement, EM 231 Thermocouple module
and EM 231 RTD module.
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1 EM 23 Thermocouple module provides analog inputs for
thermocouples. A thermocouple is a temperature sensor
made from two dissimilar metals joined at a point called a
junction. A thermocouple produces a small voltage that is
dependent upon temperature. Various types of thermocouples
are available for use in different temperature ranges. Two
versions of EM 23 Thermocouple modules are available, one
for four thermocouples and one for eight thermocouples. Each
version is compatible with J, K, T, E, R, S, or N thermocouples,
but the thermocouples used with a specific module must be of
the same type.
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1 EM 23 RTD module provides analog inputs for resistance
temperature detectors (RTDs). An RTD is a temperature
sensor made from a metal, such as platinum, nickel, or copper,
that varies in resistance in a predictable manner as temperature
varies. Two versions of the EM 23 RTD module are available,
one with two analog inputs and one with four analog inputs.
Either version can be used with a variety of RTD types, but the
RTDs used with a specific module must be of the same type.
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SIMATIC
S7 - 200
SF/DIAG
RUN
STOP
00
01
.0 .1 .2 .3 .4 .5 .6 .7
I0
.0 .1 .2 .3 .4 .5 .6 .7
.0 .1
I1
.0 .1 .2 .3 .4 .5
CPU 224
AC/DC/RLY
+24
VDC
EM 231
AI4 - TC
SF
243-7PD22-0XA0
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PORT
0
A+ A- B+ B- C+ C- D+ D-
L+
M
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S7-200 PLC with EM 231 Expansion Module
+
-
A+ A- a+ a- B+ B- b+ b-
Configuration
L+
M
Refer to the S7-200 Programmable
Controller System Manual for
Configuration DIP Switch Positions
24 VDC
+
-
Configuration
Refer to the S7-200 Programmable
Controller System Manual for
Configuration DIP Switch Positions
24 VDC
EM 231 Thermocouple module, 4 Input Version
69
EM 231 RTD module, 2 Input Version
SIWAREX MS Weighing module provides a simple, easy
to install approach for weighing and force measurement
applications. SWAREX MS Weighing module is designed to
measure the voltage produced by sensors commonly used to
measure weight, force, or torque.
SIWAREX MS Weighing
Module
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SIWAREX MS is easily integrated into an S7-200 PLC system
as an expansion module. This makes information obtained from
SIWAREX MS available to other components of the automation
system. In addition, Siemens offers a wide variety of compatible
sensors and other components.
S7-200 PLC with SIWAREX MS Module
SIMATIC
S7 - 200
SF/DIAG
RUN
STOP
00
.0 .1 .2 .3 .4 .5 .6 .7
I0
.0 .1 .2 .3 .4 .5 .6 .7
I1
CPU 224XP
DC/DC/DC
.0 .1
.0 .1 .2 .3 .4 .5
214-2AD23-0XB0
PORT
0
SF
+24
VDC
I
NET
p
---I
SIWAREX MS
->0<-
MAX
7MH4930-0AA01
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PORT
1
01
SIMATIC PANEL
TOUCH
SIWAREX MS
12.78 kg
T
pT
+9e
wrp
min
err
ss
Lim 1 Lim 2
erase
list
>0<
Tp
T
ezelle
d Cell
/ Loa
o
en
T
><
XR
SIWARE
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Touch Panel TP 177micro
70
SIWAREX R Load Cell
Review 6
2.
CPU 22 and CPU 222 support ____ high speed
counters. CPU 224, CPU 224XP, CPU 224XPsi, and CPU
226 support ____ high speed counters.
3.
S7-200 PLCs have two ___________ that create either
a high-speed pulse train or a pulse-width modulated
waveform.
4.
________ and ________ communication processors
are used to connect an S7-200 PLC to an Industrial
Ethernet network.
5.
_________ module allows connection of an S7-200 CPU
(CPU222 and above) to a PROFIBUS-DP network as a
slave.
6.
_________ module allows connection of an S7-200 CPU
(CPU222 and above) to an AS-I network as a master.
7.
Two versions of EM 23 Thermocouple module are
available, one for ____ thermocouples and one for ____
thermocouples.
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1 Two versions of EM 23 RTD module are available, one
for ____ RTDs and one for ____ RTDs.
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Three types of SIMATIC counters available in the
S7 200 instruction set are ____________, ____________
and ____________.
1
.
Review Answers
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) discrete; 2) discrete; 3) CPU; 4) Ladder logic; 5) Statement
list, function block diagrams; 6) scan; 7) 024; 8) firmware;
9) RS-485.
1
Review 2
1
1
1
) a: input module, b: CPU, c: output module, d: programming
device, e: operator interface; 2) 2; 3) 6; 4) 0 0, 000 0000, A.
Review 1
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1
1
1
1
) Count Up Counter (CTU), Count Down Counter (CTD), Count
Up/Down Counter (CTUD); 2) 4, 6; 3) PTO/PWM generators;
4) CP 243- , CP 243- IT; 5) EM 277 PROFIBUS-DP
6) CP 243-2 AS-Interface Master; 7) 4, 8; 8) 2, 4.
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Review 6
) 224XP; 2) On-Delay Timer (TON), Retentive On-Delay Timer
(TONR), Off-Delay Timer (TOF) ; 3) 3276.7 seconds;
4) Retentive On-Delay Timer (TONR); 5) On-Delay Timer (TON),
Off-Delay Timer (TOF), Pulse Timer (TP).
1
Review 5
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) a: box, b: normally open contact, c: coil;
2) AND Function - a: 0, b: 0, c: 0, d: ,
OR Function - e: 0, f: , g: , h: ;
3) I0. , I0.0, Q0.0.
1
Review 4
1
1
) CPU 22 , CPU 222, CPU 224, CPU 224XP, CPU 224XPsi,
CPU 226; 2) b; 3) 2, 7; 4) 8, 6; 5) 4, 0; 6) Q0.3; 7) DIN.
1
Review 3
72
73
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Final Exam
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You can test your knowledge by taking the final exam for this
course online at http://www.usa.siemens.com/step. This
web page provides links to a variety of our quickSTEP online
courses. To complete the final exam for this course, click on the
Basics of PLCs link.
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Next, move your mouse over to the left so that the navigation
bar pops out and select the Final Exam link. The final
exam page will appear. Before taking the final exam, it is
recommended that you delete the temporary files on your
computer. For most versions of Internet Explorer, you can do
this by selecting Internet Options from the Tools menu and
then clicking on the Delete Files button. If you do not perform
this step, you may see a score of 0% after you submit your
exam for grading.
After you complete the final exam, click on the Grade the
Exam button at the bottom of the page. Your score on the exam
will be displayed along with the questions that you missed.
If you score 70% or better on the exam, you will be given two
options for displaying and printing a certificate of completion.
The Print Certificate option allows you to display and print the
certificate without saving your score in our database and the
Save Score option allows you to save your score and display
and print your certificate.
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