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SIEMENS SIMATIC S7SIEMENS SIMATIC S7
INTRODUCTION TOINTRODUCTION TO
PROGRAMMABLEPROGRAMMABLELOGICLOGIC
CONTROLCONTROL
Revision 2
ASSESSMENTASSESSMENTASSESSMENTASSESSMENT
»Practical Test 1 – 20%
»Practical Test 2 – 20%
»Assignment – 20%»Assignment – 20%
»Final Exam – 30%
»Key Qualification – 10%
MODULE OBJECTIVESMODULE OBJECTIVESMODULE OBJECTIVESMODULE OBJECTIVES
Upon completion of this course, the participants will be able to:
» explain the basic ideas on PLC such as PLC components’
signaling, I/O addressing and program execution;
» apply PLC programming method such as LAD, FBD and STL using
Siemens STEP 7 software;
» define and explain Siemens STEP 7 PLC software such as RS,
timers, counters, load and transfer commands, comparisons and
arithmetic functions.
Topic 1Topic 1Topic 1Topic 1
Handout section 1.0
Basic Principle of Basic Principle of
Control TechnologyControl Technology
Basic Principle of Basic Principle of
Control TechnologyControl Technology
PPROGRAMMABLE ROGRAMMABLE LLOGIC OGIC CCONTROL ONTROL (PLC)(PLC)::
“ A digital electronic device that uses a
PLCPLCPLCPLC
“ A digital electronic device that uses a
programmable memory to store instructions
and to implement specific functions such as
logic, sequence, timing, counting and
arithmetic to control machines and process. “
What is CONTROL?
“ CONTROL is the process in a system in which
Definition of ControlDefinition of ControlDefinition of ControlDefinition of Control
“ CONTROL is the process in a system in which
one or several input variables influence other
variables “
DIN 19226
CC
OO
SS
YY PP
INFORMATION SENSORS
A Simple View of a Control SystemA Simple View of a Control SystemA Simple View of a Control SystemA Simple View of a Control System
OO
NN
TT
RR
OO
LL
YY
SS
TT
EE
MM
PP
LL
AA
NN
TT
COMMANDS ACTUATORS
CONTROL
SYSTEM
Types of Control SystemTypes of Control SystemTypes of Control SystemTypes of Control System
SYSTEM
OPEN-LOOP
CONTROL SYSTEM
CLOSED-LOOP
CONTROL SYSTEM
In open-loop control systems, output variables are
influenced by the input variables.
OpenOpen--loop Control Systemloop Control SystemOpenOpen--loop Control Systemloop Control System
LLLL
NN
It is characterized by continuous comparison of the
desired value (or set point) with the actual value of the
controlled variable.
ClosedClosed--loop Control Systemloop Control SystemClosedClosed--loop Control Systemloop Control System
CC
XsXsXiXi
Xi > XsXi > Xs
Xi < XsXi < Xs
LL
NN
Xi Xi -- Required valueRequired value
Xs Xs -- Actual valueActual value
The essential difference between programmable control and traditional control technology may be summed up as follows:
PLC and Conventional Control SystemPLC and Conventional Control SystemPLC and Conventional Control SystemPLC and Conventional Control System
Handout section 1.1
» The functions are no longer determined by the wiring, but
rather by the program
» Programming is simplified to enable symbols familiar to
the control engineer to be used (contacts or logic graphic
symbols)
LL
S1S1 S1S1 S2S2
24 VDC24 VDC
Hardwire and PLC Wiring DiagramsHardwire and PLC Wiring DiagramsHardwire and PLC Wiring DiagramsHardwire and PLC Wiring Diagrams
Handout section 1.3
NN
S2S2
K1K1
PLCPLC
K1K1
HardwireHardwire PLCPLC
0 V0 V
K1K1
ComparisonComparisonComparisonComparison
Hardwired control systemsHardwired control systems
» The functions are determined
by the physical wiring.
Programmable control systemProgrammable control system
» The functions are determined
by a program stored in the
memory.
» Changing the function means
changing the wiring
» Can be contact-making type
(relays, contactors) or
electronic type (logic circuits)
memory.
» The control functions can be
changed simply by changing
the program.
» Consist of a control device, to
which all the sensors and
actuators are connected.
» During the late 1960s, General Motors (USA) was interested in the
computer application to replace the hardwire systems.
» Bedford Associates (Modicon) and Allen Bradley responded to
General Motors.
HISTORY OF PLCHISTORY OF PLCHISTORY OF PLCHISTORY OF PLC
General Motors.
» The name given was “Programmable Controllers” or PC.
» Programmable Logic Controller or PLC was a registered trademark
of the Allen Bradley.
» Later, PC was used for “Personal Computer” and to avoid
confusion PLC for “Programmable Controller” and PC for a
personal computer.
» Implementing changes and correcting errors
» Pilot run - trial / test run
ADVANTAGES OF PLC COMPARED TO HARDWIREADVANTAGES OF PLC COMPARED TO HARDWIREADVANTAGES OF PLC COMPARED TO HARDWIREADVANTAGES OF PLC COMPARED TO HARDWIRE
» Visual observation - online monitoring
» Speed of operation
» Reliability
» Documentation
CONVEYOR LINE
PLC Application ExamplePLC Application ExamplePLC Application ExamplePLC Application Example
WORKSTATION #1 WS #2 WS #3
FLOW OF MATERIAL
» Input devices
◊ Sensors
◊ Switches etc.M
PLC Control SystemPLC Control SystemPLC Control SystemPLC Control System
» Output devices
◊ Relays
◊ Lamps etc
» PLC
WS #1 WS #2 WS #3
0 0 3 2PLC
Familiarization with STEP 7Familiarization with STEP 7Familiarization with STEP 7Familiarization with STEP 7
Handout section 2.0 ( Topic 2 )
POWERPOWER
SUPPLYSUPPLY
PG/PG/
PCPC
Basic Structure of a PLCBasic Structure of a PLCBasic Structure of a PLCBasic Structure of a PLC
Handout section 1.4
CENTRALCENTRAL
PROCESSINGPROCESSING
UNIT (CPU)UNIT (CPU)
INPUTINPUT
MODULESMODULESOUTPUTOUTPUT
MODULESMODULES
MEMORYMEMORY
(EPROM/RAM)(EPROM/RAM)
USERUSERPROGRAMPROGRAMUSERUSER
PROGRAMPROGRAM
PLC Inputs / Outputs (I/Os)PLC Inputs / Outputs (I/Os)PLC Inputs / Outputs (I/Os)PLC Inputs / Outputs (I/Os)
PLCPLC
PROGRAMPROGRAM
(LOGIC)(LOGIC)
PROGRAMPROGRAM
(LOGIC)(LOGIC)
InputInputDevicesDevices
OutputOutputDevicesDevices
InputInput
» Input card
» Converter
Input ConnectionsInput ConnectionsInput ConnectionsInput Connections
InputInputDevicesDevices
» Converter
◊ field voltage to 5V
acceptable by the CPU
Input Interface / ModuleInput Interface / ModuleInput Interface / ModuleInput Interface / Module
Handout section 1.4.1
From field wiring
Detection
Bridge
Signal
To CPU / Memory
Signal
Conditioning
Threshold
Decision
Logic
Logic Status
Light
Opto-Isolation
» Output card
Output ConnectionsOutput ConnectionsOutput ConnectionsOutput Connections
» Converter
◊ 5V to field voltage
to drive field devices
OutputOutputDevicesDevices
Output Interface / ModuleOutput Interface / ModuleOutput Interface / ModuleOutput Interface / Module
From CPU / Memory
Logic Status
Light
Opto-Isolation
Logic
Handout section 1.4.2
To field wiring
Switching
Circuitry
Protection
Circuitry
Opto-Isolation
IN
OUT
M
PLC
Input/output ConnectionsInput/output ConnectionsInput/output ConnectionsInput/output Connections
NPUTS
UTPUTS
WS #1 WS #2 WS #3
0 0 32 PLC
PLC
Logic
Input / Output ModulesInput / Output ModulesInput / Output ModulesInput / Output Modules
» Digital input modules adapt digital signals e.g. from proximity
sensors
» Digital output modules convert the internal signal level of PLC into
digital process signals e.g. relaysdigital process signals e.g. relays
» Analog input modules adapt analog process signals e.g. from
transducers
» Analog output modules convert internal digital values of the PLC to
analog process signals e.g. temperature controller
Central Processing Unit (CPU)Central Processing Unit (CPU)Central Processing Unit (CPU)Central Processing Unit (CPU)
What is a CPU?What is a CPU?
» The “brain” of a PLC
Handout section 1.4.3
» Controlled by a program called the executive or operating
system (OS)
» The executive is a collection of supervisory programs
permanently stored in memory
CPUCPUCPUCPU
Four basic types of CPU operations:Four basic types of CPU operations:
» Input and output operation
» Arithmetic and logic
» Reading or changing contents of memory locations
» Jump operations
CPUCPUCPUCPU
ACCUMULATOR
INTERNALPROGRAMMEMORY
(RAM)
MEMORYSUBMODULE
(EPROM/EEPROM/
RAM)
PROCESSOR
TIMERS, COUNTERS,
Memory
PII PIQ
SERIALINTERFACE
» The CPU reads in input signal states, processes the control
program and controls the outputs.
» The CPU provides internal Memory, timers and counters.
CPUCPUCPUCPU
» Restart procedure can be preset and errors can be diagnosed
using the CPU’s LEDs.
» The overall Reset on the CPU is used to delete the contents of the
RAM.
» A PG or a Memory submodule is used to transfer the control
program to the CPU.
Program MemoryProgram MemoryProgram MemoryProgram Memory
Program memory
Handout section 1.4.4
RAM (Random Access Memory)
• the memory contents can be
read and written (modified)
• memory contents will be lost
when the supply voltage fails
ROM (Read Only Memory)
• the memory contents can be
read, but cannot be modified
Types of Program MemoryTypes of Program MemoryTypes of Program MemoryTypes of Program Memory
Programmable(Read-write memory)
Program memory
Non-programmable
Alterable
UV erasableEPROM / REPROM
Semiconductor RAM
Non-alterableROM / PROM
Electrically erasableEEPROM / EAPROM
SemiconductorEEPROM / EAPROM
Memory SubmodulesMemory SubmodulesMemory SubmodulesMemory Submodules
» EPROM SUBMODULE
An ultraviolet erasing device is used to delete the contents of the
submodule
» EEPROM SUBMODULE » EEPROM SUBMODULE
EEPROM submodule can be programmed or erased using a
programmer
» RAM SUBMODULE
Can be used in addition to program storage; and used to test a
control program during system startup
» The power supply module supplies the operational voltage for the
PLC and provides backup for the RAM with a battery
» Backup battery
Power Supply ModulePower Supply ModulePower Supply ModulePower Supply Module
Handout section 1.4.5
» The backup battery maintains the program and data when the PLC
is switch off
» The backup battery has a service life of approximately 2 years
PG
Input
External power supply
Hardware SummaryHardware SummaryHardware SummaryHardware Summary
PS951CPU
Inputmodule
Outputmodule
Inputdevices
Outputdevices
How Does a Programmable Controller Work?How Does a Programmable Controller Work?How Does a Programmable Controller Work?How Does a Programmable Controller Work?
Handout section 1.5
ProgramProcessor
24 VDC
Sensors
Power
Supply
Program
MemoryProcessor
Input modules
Output modules
GND
Actuators / Annunciators
Steps of OperationSteps of OperationSteps of OperationSteps of Operation
» The sensors are connected to the INPUT MODULES
» The processor in the CPU MODULE executes the program and
scans the individual input for presence or absence of voltagescans the individual input for presence or absence of voltage
» Depending on the state of the inputs, the processor directs the
OUTPUT MODULES to switch voltages
» The ACTUATORS or ANNUNCIATORS are switched “ON” or
“OFF” according to the voltage states
Signal States and Sensor ContactsSignal States and Sensor ContactsSignal States and Sensor ContactsSignal States and Sensor Contacts
» There are only two different states:
SIGNAL STATE “0” = voltage not present = OFF
SIGNAL STATE “1” = voltage present = ON
Handout section 1.6
» The sensor is a The sensor is Voltage at input Signal state
NO contact activated present 1
NO contact not activated not present 0
NC contact activated not present 0
NC contact not activated present 1
Addressing of Inputs and OutputsAddressing of Inputs and OutputsAddressing of Inputs and OutputsAddressing of Inputs and Outputs
» The addressing of inputs and outputs are identified by an operand identifiers and the parameter
» Operand identifiers:
Handout section 1.7
» Operand identifiers:
I - Input
Q - Output
» Parameter: (consists of a byte and a bit address)
0.0 … 0.7 (where 0. is the byte; 0…7 are the bit addresses)
1.0 … 1.7
Types of AddressingTypes of AddressingTypes of AddressingTypes of Addressing
Absolute
» example:» A I 0.0
» = Q 8.0
» A I0.4
» = Q20.5
Symbolic
» example:» A “System_On”
» = “System_On”
» A “M_FORW”
» = “MOTOR_FOR”» = Q20.5
» Call FC18» = “MOTOR_FOR”
» Call “COUNT”
Symbol Address Data Type Comment
MOTOR_FOR Q20.5 BOOL Motor moves forward
COUNT FC18 FC18 Count bottles
SYSTEM_ON I0.0 BOOL Switch system ON
SYSTEM_ON Q8.0 BOOL Indicator: “System is ON”
M_FORW I0.4 BOOL Pushbutton: Motor forward
Max. 24 character Max. 80 character
Handout section 1.8.1
LAD - Ladder Diagram
( )I 0.0 I 0.1 Q 4.0
Program Representation Program Representation -- LADLADProgram Representation Program Representation -- LADLAD
» The graphical representation of a control task using symbols to
DIN 19239
» Very similar to traditional circuit diagrams, but the current paths are
arranged horizontally instead of vertically
Program Representation Program Representation -- FBDFBDProgram Representation Program Representation -- FBDFBD
FBD - Function Block Diagram
&I 0.0
I 0.1Q 4.0
Handout section 1.8.2
» The graphical representation of a control task using symbols to
DIN 40700 and DIN 19239
» Inputs are arranged on the left side while outputs on the right
I 0.1
Program Representation Program Representation -- STLSTLProgram Representation Program Representation -- STLSTL
STL - Statement List
A I 0.0
A I 0.1
= Q 4.0
Handout section 1.8.3
» The control statement describes the task with mnemonic
abbreviations of function designation (DIN 19239)
» Each method of representation has special characteristics and
specific limits
» If certain rules are followed, translation into all three methods of
representation is possible
= Q 4.0
Operation And OperandOperation And OperandOperation And OperandOperation And Operand
Handout section 1.8.4
Operation;
Describes the function to be carried out (what is to be done)
e.g Binary operations, Digital operations and Organizational operations
Operand;
START FROM HERE
FBDFBDFBDFBD
OPERAND + OPERATION
STLSTLSTLSTL
OPERATION + OPERAND
A I 0.0
Operation And OperandOperation And OperandOperation And OperandOperation And Operand
LADLADLADLAD
OPERATION + OPERAND
I 0.0 M 80.0
Handout section 1.8.4
I 0.0
OPERATION + OPERAND
= Q 4.0
A I 0.0A M 80.0
= Q 4.0( )
Q 4.0
I 0.0 M 80.0&
I 0.0
M 80.0
Program ExecutionProgram ExecutionProgram ExecutionProgram Execution
PLC Scan Function:PLC Scan Function:
» Read the status of all inputs and outputs
Handout section 1.9
» Read the status of all inputs and outputs
» Examine the application program instructions
» Execute the control program
Linear Program ScanningLinear Program ScanningLinear Program ScanningLinear Program Scanning
» Statements are scanned linearly
» At the end of the program, scanning starts again from the
beginning
Handout section 1.9.1
beginning
» This is also referred to as cyclical scanning
» Linear program scanning is used mainly for simple, small-scale control schemes
» OB = Organization Block
» Every program must have OB1
OB1OB1OB1OB1
Linear program scanning
OB1
» When the PLC is set to run, the
PLC will look for OB1 only in the
user memory and execute it
» Other blocks can be called from
OB1 with the “jump” commandCyclic program execution
A I 0.0A I 0.1= Q 4.0:::BE
» Complex tasks are subdivided
into clearly differentiated sub-
tasks
Handout section 1.9.2
Structured Program ScanningStructured Program ScanningStructured Program ScanningStructured Program Scanning
OB1
JU FC 1
FC1
A I 0.0A I 0.1= Q 4.0:::
Cyclic
pro
gra
m e
xecution
Operatingsystem
» i.e. the program is divided into
small, easy-to-follow program
blocks, organized according to
different functions
JU FC 1
JU FC 4:::BE
:BE
FC4
A Q 4.0A I 0.2= Q 5.0:::BE
Cyclic
pro
gra
m e
xecution
Structured program scanning
Linear programming
OB1
Network 1
A I 0.6
A I 0.7
= Q 4.2
Network 2
A I 0.7
Network 1
JU FC 1
OB 1
Network 1
A I 0.6
A I 0.7
= Q 4.2
Network 2
A I 0.7
A I 0.5
= Q 4.3
FC 1
Structured programming
A I 0.7
A I 0.5
= Q 4.3
Network 3
A Q 4.2
A I 0.2
= Q 5.5
BE
JU FC 1
JU FC 4
BE
= Q 4.3
BE
Network 1
A Q 4.2
A I 0.2
= Q 5.5
BE
FC 4
Program ExecutionProgram ExecutionProgram ExecutionProgram Execution
Handout section 1.9.3
A I 0.0
A I 0.1
= Q 4.0P P
24 VDC GNDInput
moduleProcess
input imageProcess
output image
Program inthe RAM
Outputmodule
I 0.1
I 0.0
Q 4.0
1
0
0
= Q 4.0
O I 0.5
O I 0.7
= Q 4.3
BE:
P
I
I
P
I
Q
Input cycle Program execution Output cycle
I 0.5
I 0.7
Q 4.3
1
1
1
» A buffer of input signals
» Update just before program
execution starts
Update PII
Execute
Program
PII PII -- Process Input ImageProcess Input ImagePII PII -- Process Input ImageProcess Input Image
» Not updated during program
execution
» Logic executed based on status in PII
» Prevent signal transition during
program cycle to affect the program
Program
Logic
Update Output
» Updated by the
program logic during
program execution
OB1
PIQ PIQ -- Process Output ImageProcess Output ImagePIQ PIQ -- Process Output ImageProcess Output Image
program execution
» The contents of PIQ
are transferred to the
output module at the
end of OB1
OB1 PIQ
Copy PIQ to Output Module
BLOCK TYPESBLOCK TYPESBLOCK TYPESBLOCK TYPES
» ORGANISATION BLOCKS (OB) – Interface between the operating system and the user program
» FUNCTIONS (FC) - Contains a partial functionality of the program
» DATA BLOCKS (DB) – Are data areas of the user program in which user data are managed in a structured manner
Handout section 1.9.4
data are managed in a structured manner
» SYSTEM FUNCTION BLOCKS (SFB), SYSTEM FUNCTIONS (SFC) -SFBs and SFCs are integrated in the S7 CPU and allow you access to some important system functions
» FUNCTION BLOCKS (FB) - FBs are blocks with a “memory” which you can program yourself
» INSTANCE DATA BLOCKS (DB) - Instance DBs are associated with the block when an FB/SFB is called. They are created automatically during compilation
FC 1
FC 4
FC 7
A I ....
..
..
Block Nesting DepthBlock Nesting DepthBlock Nesting DepthBlock Nesting Depth
JU FC 1
..
...
..
BE
OB1JU FC4
..
...
BE
JU FC 7
..
...
BE
..
..
BE
The Operand Areas (for Siemens S5The Operand Areas (for Siemens S5--95U PLC)95U PLC)The Operand Areas (for Siemens S5The Operand Areas (for Siemens S5--95U PLC)95U PLC)
» I (Input)
Interface from the process to the programmable controller
» Q (Output)
Interface from programmable controller to the process
Handout section 1.9.5
» M (Memory/Flag)
Memory for intermediate results of binary operations
» T (Timer)
Memory for implementing timers
» C (Counter)
Memory for implementing counters
The Addressing of Siemens S7The Addressing of Siemens S7The Addressing of Siemens S7The Addressing of Siemens S7
Operand Areas Addressing
Input (I) 0.0 to 0.7
1.0 to 1.7
2.0 to 2.7
Handout section 1.9.6
3.0 to 3.7
Output (Q) 4.0 to 4.7
5.0 to 5.7
8.0 to 8.7
9.0 to 9.7
Counters (C) 0 to 63
Timers (T) 0 to 127
Topic 3Topic 3Topic 3Topic 3
Handout section 3.0
Programming Basic Programming Basic
FunctionsFunctions
Programming Basic Programming Basic
FunctionsFunctions
The Stages of Project PlanningThe Stages of Project PlanningThe Stages of Project PlanningThe Stages of Project Planning
Description of the Problem
Assignment Lists
Handout section 3.1
Rough Structure of the Control System
Program Structure
Detailed Structure of the Control System
The Stages of Project PlanningThe Stages of Project PlanningThe Stages of Project PlanningThe Stages of Project Planning
Problem Description
» it consists of process schematic, a short description of the task
definition, and a list of the sensors and actuators
Assignment ListAssignment List
» the sensors and actuators are allocated to the parameters of the
programmable controller
» it contains a short functional description as well as the device
identifier
The Stages of Project PlanningThe Stages of Project PlanningThe Stages of Project PlanningThe Stages of Project Planning
Rough Structure of the Control System
» it contains all sub-functions of the process with relevant sensors,
actuators and indicators
Program StructureProgram Structure
» it determines the order in which the LAD, FBD or STL diagram to
be drafted
Detailed Structure of the Control System
» using the assignment list and the program structure, the flow chart
contained in the rough structure is refined
Programming AND OperationProgramming AND OperationProgramming AND OperationProgramming AND Operation
( )I 0.0 I 0.1 Q 4.0
LAD
Handout section 3.2
STL
A I 0.0A I 0.1= Q 4.0
&I 0.0
I 0.1
Q 4.0
FBD
OR OperationOR OperationOR OperationOR Operation
Handout section 3.3
LAD
( )I 0.0
I 0.1
Q 4.0
STL
O I 0.0O I 0. 1= Q 4.0
>= 1
FBD
I 0.0
I 0.1
Q 4.0
I 0.1
AND AND -- before before -- OR OperationOR OperationAND AND -- before before -- OR OperationOR Operation
Handout section 3.4
( )I 0.0 I 0.1
I 0.2 I 0.3
Q 4.0LAD
I 0.0 I 0.2
STLA I 0.0A I 0.1OA I 0.2A I 0.3= Q 4.0
I 0.2 I 0.3
I 0.1 I 0.3
I 0.0
I 0.1
I 0.2
I 0.3
Q 4.0
FBD
>= 1
&
&
STL
OR OR -- before before -- AND OperationAND OperationOR OR -- before before -- AND OperationAND Operation
Handout section 3.5
( )I 0.0 I 0.1
I 0.2 I 0.3
Q 4.0LAD
I 0.0 I 0.2STLA (O I 0.0O I 0.2)A (O I 0.1O I 0.3)= Q 4.0
I 0.1 I 0.3
I 0.0
I 0.1
I 0.2
I 0.3
Q 4.0
FBD
&
>= 1
>= 1
Handout section 3.6
Programming of NC Contacts and NO ContactsProgramming of NC Contacts and NO ContactsProgramming of NC Contacts and NO ContactsProgramming of NC Contacts and NO Contacts
» Physical connection PLC programming The sensor is Signal state
NO contact NO contact activated 1
NO contact NO contact not activated 0NO contact NO contact not activated 0
NO contact NC contact activated 0
NO contact NC contact not activated 1
NC contact NO contact activated 0
NC contact NO contact not activated 1
NC contact NC contact activated 1
NC contact NC contact not activated 0
Latching OutputLatching OutputLatching OutputLatching Output
Handout section 3.7
S1
S2
K1S3
S4
K2
SET Priority / Dominant SET RESET Priority / Dominant RESET
S2
K1
S4
K2
RS Memory FunctionRS Memory FunctionRS Memory FunctionRS Memory Function
Handout section 3.8
R
S2S3
S4
K2
SET Priority / Dominant SET
=S Q
S1
( )K1
S4
K2
RS Memory FunctionRS Memory FunctionRS Memory FunctionRS Memory Function
S
S3S1
S2
K1
RESET Priority / Dominant RESET
=R Q
S4
( )K2
S2
K1
Try This !Try This !Try This !Try This !
Will the output Q 4.0 be
activated when you
activate:
» I 0.0 and I 0.1 ?( )I 0.0 I 0.1 Q 4.0
LAD
» I 0.2 and I 0.3 ?
» I 0.4 and I 0.5 ?
( )I 0.2 I 0.3 Q 4.0
( )I 0.4 I 0.5 Q 4.0
The AnswerThe AnswerThe AnswerThe Answer
» I 0.0 and I 0.1 = NO!
» I 0.2 and I 0.3 = NO!» I 0.2 and I 0.3 = NO!
» I 0.4 and I 0.5 = YES …… but why ?
When I0.0 and I0.1 Are Activated...When I0.0 and I0.1 Are Activated...When I0.0 and I0.1 Are Activated...When I0.0 and I0.1 Are Activated...
» the PLC registers in the PIQ that Q 4.0 is “1”
( )I 0.0 I 0.1 Q 4.0
LAD
I 0.2 I 0.3 Q 4.0» the PLC registers in the PIQ
that Q 4.0 is “0”
» the PLC registers in the PIQ that Q 4.0 is “0”
so, Q 4.0 = “0”
( )I 0.2 I 0.3 Q 4.0
( )I 0.4 I 0.5 Q 4.0
When I0.2 and I0.3 Are Activated...When I0.2 and I0.3 Are Activated...When I0.2 and I0.3 Are Activated...When I0.2 and I0.3 Are Activated...
» the PLC registers in the PIQ that Q 4.0 is “0”
( )I 0.0 I 0.1 Q 4.0
LAD
I 0.2 I 0.3 Q 4.0» the PLC registers in the PIQ
that Q 4.0 is “1”
» the PLC registers in the PIQ that Q 4.0 is “0”
so, Q 4.0 = “0”
( )I 0.2 I 0.3 Q 4.0
( )I 0.4 I 0.5 Q 4.0
When I0.4 and I0.5 Are Activated...When I0.4 and I0.5 Are Activated...When I0.4 and I0.5 Are Activated...When I0.4 and I0.5 Are Activated...
» the PLC registers in the PIQ that Q 4.0 is “0”
( )I 0.0 I 0.1 Q 4.0
LAD
I 0.2 I 0.3 Q 4.0» the PLC registers in the PIQ
that Q 4.0 is “0”
» the PLC registers in the PIQ that Q 4.0 is “1”
this time, Q 4.0 = “1”
( )I 0.2 I 0.3 Q 4.0
( )I 0.4 I 0.5 Q 4.0
Priority and PIQPriority and PIQPriority and PIQPriority and PIQ
The Problem of Repetitive OutputsThe Problem of Repetitive OutputsThe Problem of Repetitive OutputsThe Problem of Repetitive Outputs
» Therefore, when the same output is used more than once in the
program, only the last state of the output will be valid due to the
PLC dynamically updating the PIQ (Process Output Image)
» MEMORY = Memory for intermediate results of binary » MEMORY = Memory for intermediate results of binary operations
» Memory can be treated as flags/variables
» Memory can be used to solve the problem of repetitive outputs
Using Memory…...Using Memory…...Using Memory…...Using Memory…...
( )I 0.0 I 0.1 M 100.0
( )I 0.2 I 0.3 M 100.1
I 0.4 I 0.5 M 100.2( )
I 0.4 I 0.5 M 100.2
( )M 100.0 Q 4.0
M 100.1
M 100.2
RLO STATA Q 4.0 …… ……
Result of Logic Operation (RLO)Result of Logic Operation (RLO)Result of Logic Operation (RLO)Result of Logic Operation (RLO)
Q 4.0A Q 4.0 …… ……A ( …… …… O I 0.1 …… …… O I 0.2 …… …… O I 0.3 …… …… )= Q 5.0 …… ……
>=1I 0.0
I 0.1
I 0.2
Q 5.0&
Mathematics Logic Operation
Multiplication Before Addition
4 X 8 + 3 X 2 = 38AND before OR
Parenthesized FunctionParenthesized FunctionParenthesized FunctionParenthesized Function
4 X 8 + 3 X 2 = 38
RLO STATA I 0.0 1 1A I 0.1 1 1O 1 \A I 0.2 0 0A I 0.3 0 1= Q 4.0 1 1
Addition Before Multiplication
4 X (8 + 3 ) X 2 = 88
Parenthesized FunctionParenthesized FunctionParenthesized FunctionParenthesized Function
Mathematics Logic Operation
OR before AND4 X (8 + 3 ) X 2 = 88
RLO STATA I 0.0 1 1A ( 1 \O I 0.1 1 1O I 0.2 1 0) 1 \A I 0.3 1 1= Q 4.1 1 1
Topic 4Topic 4Topic 4Topic 4
Handout section 4.0
Numerical Systems and Numerical Systems and
Data FormatsData Formats
Numerical Systems and Numerical Systems and
Data FormatsData Formats
Comparison of Number SystemsComparison of Number SystemsComparison of Number SystemsComparison of Number Systems
DecimalNumber
HexadecimalNumber
BinaryNumber
102
101
100
162
161
160
24
23
22
21
20
100 10 1 256 16 1 16 8 4 2 1
0 0 0 0 0 0 0 0 01 1 0 0 0 0 1
2 2 0 0 0 1 0
3 3 0 0 0 1 1
Handout section 4.1
3 3 0 0 0 1 1
4 4 0 0 1 0 0
5 5 0 0 1 0 1
6 6 0 0 1 1 0
7 7 0 0 1 1 1
8 8 0 1 0 0 0
9 9 0 1 0 0 1
1 0 A 0 1 0 1 0
1 1 B 0 1 0 1 1
1 2 C 0 1 1 0 0
1 3 D 0 1 1 0 1
1 4 E 0 1 1 1 0
1 5 F 0 1 1 1 1
1 6 1 0 1 0 0 0 0
1 7 1 1 1 0 0 0 1
Binary and HexadecimalBinary and HexadecimalBinary and HexadecimalBinary and Hexadecimal
Word Address
IW0
Byte Addresses
High Byte Low Byte
Bit, Byte and Word AddressesBit, Byte and Word AddressesBit, Byte and Word AddressesBit, Byte and Word Addresses
Handout section 4.2
High Byte Low Byte
IB0 IB1
215
214
213
212
211
210
29
28
27
26
25
24
23
22
21
20
Bit Addresses
I0.7
I0.6
I0.5
I0.4
I0.3
I0.2
I0.1
I0.0
I1.7
I1.6
I1.5
I1.4
I1.3
I1.2
I1.1
I1.0
Force Variable and Data FormatForce Variable and Data FormatForce Variable and Data FormatForce Variable and Data Format
Force Variable
» Display the signal status from memory (PII, PIQ and flag) of the
CPU
Handout section 4.3
CPU
» Used to access the system data area of the CPU and modify the
data
Force Variable and Data FormatForce Variable and Data FormatForce Variable and Data FormatForce Variable and Data Format
Data Format
» KM - bit pattern
» KH - hexadecimal
» KF - sign number ( - 32768 to +32767 )
» KT - time value
» KC - counter value
» KY - left hand and right hand byte (high / low byte)
» KS - alphanumeric character
Load and Transfer OperationsLoad and Transfer OperationsLoad and Transfer OperationsLoad and Transfer Operations
Characteristics:
» They are used to perform operations on a whole byte or word in
memory
» They are unconditional operations i.e. They are performed by the
processor in each cycle
Handout section 4.4
processor in each cycle
Functions:
» Exchange information between various operand areas
» Prepare times and counts for further processing
» Load constants for program processing
Load OperationLoad OperationLoad OperationLoad Operation
Byte d Byte c Byte b Byte a PII
L IB 0
L IB 1ACCUM 2 ACCUM 1
0 IB 0Byte b Byte a
0 IB 10 IB 0
IB 0
IB 1
Information from PII
Transfer OperationTransfer OperationTransfer OperationTransfer Operation
Byte d Byte c Byte b Byte a PIQ
T QB 0ACCUM 2 ACCUM 1
Byte d Byte c
Byte a QB 0
Information in the PIQ
Byte b Byte a
Arithmetic and Assignment of AccumulatorArithmetic and Assignment of AccumulatorArithmetic and Assignment of AccumulatorArithmetic and Assignment of Accumulator
Handout section 4.5
Binary Coded Decimal (BCD)Binary Coded Decimal (BCD)Binary Coded Decimal (BCD)Binary Coded Decimal (BCD)
Handout section 4.6
Topic 5Topic 5Topic 5Topic 5
Handout section 5.0
Timer OperationsTimer OperationsTimer OperationsTimer Operations
Fault Indication with Timer FunctionFault Indication with Timer FunctionFault Indication with Timer FunctionFault Indication with Timer Function
Handout section 5.0
Handout section 5.1
Inputs and Outputs of a TimerInputs and Outputs of a TimerInputs and Outputs of a TimerInputs and Outputs of a Timer
Handout section 5.2.1
Types of Timer Types of Timer -- Pulse Timer (SP)Pulse Timer (SP)Types of Timer Types of Timer -- Pulse Timer (SP)Pulse Timer (SP)
Handout section 5.2.2
Extended Pulse Timer (SE)Extended Pulse Timer (SE)Extended Pulse Timer (SE)Extended Pulse Timer (SE)
Handout section 5.2.3
On Delay Timer (SD)On Delay Timer (SD)On Delay Timer (SD)On Delay Timer (SD)
Handout section 5.2.4
Stored On Delay Timer (SS)Stored On Delay Timer (SS)Stored On Delay Timer (SS)Stored On Delay Timer (SS)
Handout section 5.2.5
Off Delay Timer (SF)Off Delay Timer (SF)Off Delay Timer (SF)Off Delay Timer (SF)
Handout section 5.3
Specifying the Time PeriodSpecifying the Time PeriodSpecifying the Time PeriodSpecifying the Time Period
Time Value and AccuracyTime Value and AccuracyTime Value and AccuracyTime Value and Accuracy
Example:
KT 500.1 500 X 0.1S 49.9s …….. 50.0s
KT 050.2 50 X 1S 49s ………... 50s
KT 005.3 5 X 10S 40s ………... 50s
Load and Transfer Timer ValueLoad and Transfer Timer ValueLoad and Transfer Timer ValueLoad and Transfer Timer Value
Return OperationsReturn OperationsReturn OperationsReturn Operations
» BE (Block End)
» the return operation is performed unconditionally
» it is always the last statement in the block
» BEU (Block End Unconditional)
Handout section 5.4
» BEU (Block End Unconditional)
» the return operation is performed unconditionally
» statements can follow BEU, but they will not be executed
» BEU is often used during commissioning so that individual parts of
the program can be tested
» BEC (Block End Conditional)
» the return is made dependent on a condition and is only performed
if the condition is satisfied
Block End Operations BEC, BEU and BEBlock End Operations BEC, BEU and BEBlock End Operations BEC, BEU and BEBlock End Operations BEC, BEU and BE
:
:JU FC1
:
:A I 0.6
:BEC
:
:BE
OB1
FC1
is always executed
is executed only
when I 0.6 = “0”
System
:A I 0.0
:JC FC 2
:
:BEU
:
:JU FC3
:BE
:BE
:
:
:BE
:
:
:BE
FC2
FC3
when I 0.6 = “0”
is executed only
when I 0.0 = “1”
is not executed
is not
executed
Topic 6Topic 6Topic 6Topic 6
Handout section 6.0
Counter OperationsCounter OperationsCounter OperationsCounter Operations
Handout section 6.0
CounterCounterCounterCounter
Counter OperationsCounter OperationsCounter OperationsCounter Operations
CU - count up
CD - count down
S - set counter to the count value (CV)
CV - the count value
R - reset the counter (count value = 0)
BI - counter output as binary number
DE - counter output as BCD number
Q - counter status
Q = 0 when count value = 0
Q = 1 when count value > 1
Handout section 6.1
Load and Transfer for CounterLoad and Transfer for CounterLoad and Transfer for CounterLoad and Transfer for Counter
Handout section 6.2
Timing DiagramTiming DiagramTiming DiagramTiming Diagram
Assign an Initial Value to a Counter (S)Assign an Initial Value to a Counter (S)Assign an Initial Value to a Counter (S)Assign an Initial Value to a Counter (S)
Assign Value (CV)
» constant KC 0 to 999
» input word IW ….....
» output word QW …...
» flag word FW …....
» data word DW …...
Counter InputCounter InputCounter InputCounter Input
Handout section 6.3
Counter OutputCounter OutputCounter OutputCounter Output
Handout section 6.4
ComparatorComparatorComparatorComparator
Types of comparison:
!=F compare for equal to
><F compare for not equal to
>F compare for greater than
>=F compare for greater than or equal to
<F compare for less than
<=F compare for less than or equal to
Comparison OperationsComparison OperationsComparison OperationsComparison Operations
» The comparison operations compare two digital values in
accumulator 1 and accumulator 2
» The result of comparison produces an RLO:» The result of comparison produces an RLO:
» Comparison satisfied RLO = “1”
» Comparison not satisfied RLO = “0”
Handout section 6.4
ComparatorComparatorComparatorComparator
THE ENDTHE ENDTHE ENDTHE END