introduction to plc (s7)

SIEMENS SIMATIC S7SIEMENS SIMATIC S7

INTRODUCTION TOINTRODUCTION TO

PROGRAMMABLEPROGRAMMABLELOGICLOGIC

CONTROLCONTROL

Revision 2

ASSESSMENTASSESSMENTASSESSMENTASSESSMENT

»Practical Test 1 – 20%

»Practical Test 2 – 20%

»Assignment – 20%

»Final Exam – 30%

»Key Qualification – 10%

Topic 1Topic 1Topic 1Topic 1

Basic Principle of Basic Principle of Control TechnologyControl TechnologyBasic Principle of Basic Principle of

Control TechnologyControl Technology

Handout section 1.0

PPROGRAMMABLE ROGRAMMABLE LLOGIC OGIC CCONTROL ONTROL (PLC)(PLC)::

“ 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. “

PLCPLCPLCPLC

What is CONTROL?

“ CONTROL is the process in a system in which

one or several input variables influence other

variables “

DIN 19226

Definition of ControlDefinition of ControlDefinition of ControlDefinition of Control

CCOONNTTRROOLL

SSYYSSTTEEMM

PPLLAANNTT

INFORMATION

COMMANDS ACTUATORS

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

In open-loop control systems, output variables are influenced by the input variables.

Open-loop Control SystemOpen-loop Control SystemOpen-loop Control SystemOpen-loop Control System

LL

NN

It is characterized by continuous comparison of the desired value (or set point) with the actual value of the controlled variable.

CC

XsXsXiXi

Xi > XsXi > Xs

Xi < XsXi < Xs

LL

NN

Xi - Required valueXi - Required value

Xs - Actual valueXs - Actual value

Closed-loop Control SystemClosed-loop Control SystemClosed-loop Control SystemClosed-loop Control System

The essential difference between programmable control and traditional control technology may be summed up as follows:

» 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)

PLC and Conventional Control SystemPLC and Conventional Control SystemPLC and Conventional Control SystemPLC and Conventional Control System

Handout section 1.1

LL

NN

S1S1

S2S2

K1K1

S1S1 S2S2

PLCPLC

K1K1

HardwireHardwire PLCPLC0 V0 V

24 VDC24 VDC

Hardwire and PLC Wiring DiagramsHardwire and PLC Wiring DiagramsHardwire and PLC Wiring DiagramsHardwire and PLC Wiring Diagrams

Handout section 1.3

K1K1

ComparisonComparisonComparisonComparison

Hardwired control systemsHardwired control systems

» The functions are determined by the physical wiring.

» Changing the function means changing the wiring

» Can be contact-making type (relays, contactors) or electronic type (logic circuits)

Programmable control systemProgrammable control system

» The functions are determined by a program stored in the 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.

» 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.

HISTORY OF PLCHISTORY OF PLCHISTORY OF PLCHISTORY OF PLC

» Implementing changes and correcting errors

» Pilot run - trial / test run

» Visual observation - online monitoring

» Speed of operation

» Reliability

» Documentation

ADVANTAGES OF PLC COMPARED TO HARDWIREADVANTAGES OF PLC COMPARED TO HARDWIREADVANTAGES OF PLC COMPARED TO HARDWIREADVANTAGES OF PLC COMPARED TO HARDWIRE

POWERPOWERSUPPLYSUPPLY

CENTRALCENTRALPROCESSINGPROCESSINGUNIT (CPU)UNIT (CPU)

INPUTINPUTMODULESMODULES

OUTPUTOUTPUTMODULESMODULES

MEMORYMEMORY(EPROM/RAM)(EPROM/RAM)

PG/PG/PCPC

Basic Structure of a PLCBasic Structure of a PLCBasic Structure of a PLCBasic Structure of a PLC

Handout section 1.4

InputInputDevicesDevices

» Input card

» Converter field voltage to 5V

acceptable by the CPU

Input ConnectionsInput ConnectionsInput ConnectionsInput Connections

Input Interface / ModuleInput Interface / ModuleInput Interface / ModuleInput Interface / Module

Handout section 1.4.1

From field wiring

To CPU / Memory

Detection Bridge

Signal Conditioning

Threshold Decision

Logic

Logic StatusLight

Opto-Isolation

» Output card

» Converter 5V to field voltage

to drive field devices

OutputOutputDevicesDevices

Output ConnectionsOutput ConnectionsOutput ConnectionsOutput Connections

Output Interface / ModuleOutput Interface / ModuleOutput Interface / ModuleOutput Interface / Module

From CPU / Memory

To field wiring

Switching Circuitry

Protection Circuitry

Logic StatusLight

Opto-Isolation

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. 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

» 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

PROCESSOR

ACCUMULATOR

TIMERS, COUNTERS,

Memory

PII

INTERNALPROGRAMMEMORY

(RAM)

PIQ

SERIALINTERFACE

MEMORYSUBMODULE

(EPROM/EEPROM/

RAM)

» The CPU reads in input signal states, processes the control program and controls the outputs.

» The CPU provides internal Memory, timers and counters.

» 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.

CPUCPUCPUCPU

Program MemoryProgram MemoryProgram MemoryProgram Memory

Program memory

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

Alterable

UV erasableEPROM / REPROM

Semiconductor RAM

Programmable(Read-write memory)

Program memory

Non-programmable

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 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

» 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

Power Supply ModulePower Supply ModulePower Supply ModulePower Supply Module


PG

PS951CPU

Inputmodule

Outputmodule

Inputdevices

Outputdevices

External power supply

Hardware SummaryHardware SummaryHardware SummaryHardware Summary

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

» 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

Handout section 1.6

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:

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

Handout section 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» Call FC18

Symbolic

» example: » A “System_On”» = “System_On”» A “M_FORW”» =

“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


LAD - Ladder Diagram

( ) I 0.0 I 0.1 Q 4.0

Program Representation - LADProgram Representation - LADProgram Representation - LADProgram Representation - LAD

» 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 - FBDProgram Representation - FBDProgram Representation - FBDProgram Representation - FBD

» 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

FBD - Function Block Diagram

&I 0.0

I 0.1Q 4.0


Program Representation - STLProgram Representation - STLProgram Representation - STLProgram Representation - STL

» 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

STL - Statement List

A I 0.0A I 0.1= Q 4.0


Operation And OperandOperation And OperandOperation And OperandOperation And Operand


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

FBDFBDFBDFBDOPERAND + OPERATION

OPERATION + OPERAND

= Q 4.0

STLSTLSTLSTLOPERATION + OPERAND

A I 0.0A M 80.0

= Q 4.0

Operation And OperandOperation And OperandOperation And OperandOperation And Operand

LADLADLADLADOPERATION + OPERAND

( )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

» Examine the application program instructions

» Execute the control program

Handout section 1.9

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

» 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

» 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” command

OB1OB1OB1OB1

Cyclic program execution

Linear program scanning

OB1

A I 0.0A I 0.1= Q 4.0:::BE

» Complex tasks are subdivided into clearly differentiated sub-tasks

» i.e. the program is divided into small, easy-to-follow program blocks, organized according to different functions


Structured Program ScanningStructured Program ScanningStructured Program ScanningStructured Program Scanning

OB1

JU FC 1

JU FC 4:::BE

FC1

A I 0.0A I 0.1= Q 4.0:::BE

FC4

A Q 4.0A I 0.2= Q 5.0:::BE

Cyc

lic p

rogr

am e

xecu

tion

Structured program scanning

Operatingsystem

Linear programming

OB1Network 1A I 0.6A I 0.7= Q 4.2Network 2A I 0.7A I 0.5= Q 4.3Network 3A Q 4.2A I 0.2= Q 5.5 BE

Network 1JU FC 1

JU FC 4

BE

OB 1

Network 1A I 0.6A I 0.7= Q 4.2Network 2A I 0.7A I 0.5= Q 4.3BE

Network 1A Q 4.2A I 0.2= Q 5.5 BE

FC 1

FC 4

Structured programming

Program ExecutionProgram ExecutionProgram ExecutionProgram Execution


A I 0.0

A I 0.1

= Q 4.0

O I 0.5

O I 0.7

= Q 4.3

BE:

PII

PIQ

24 VDC GNDInput

moduleProcess

input imageProcess

output image

Program inthe RAM

Outputmodule

Input cycle Program execution Output cycle

I 0.1

I 0.0

I 0.5

I 0.7

Q 4.0

Q 4.3

1

0

1

1

0

1

» A buffer of input signals

» Update just before program execution starts

» Not updated during program execution

» Logic executed based on status in PII

» Prevent signal transition during program cycle to affect the program

Update PII

ExecuteProgram

Logic

Update Output

PII - Process Input ImagePII - Process Input ImagePII - Process Input ImagePII - Process Input Image

» Updated by the program logic during program execution

» The contents of PIQ are transferred to the output module at the end of OB1

OB1 PIQ

Copy PIQ to Output Module

PIQ - Process Output ImagePIQ - Process Output ImagePIQ - Process Output ImagePIQ - Process Output Image

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

» 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


JU FC 1.......BE

OB1

FC 1

JU FC4.....BE

FC 4

JU FC 7.....BE

FC 7

A I ..........BE

Block Nesting DepthBlock Nesting DepthBlock Nesting DepthBlock Nesting Depth

The Operand Areas (for Siemens S5-95U PLC)The Operand Areas (for Siemens S5-95U PLC)The Operand Areas (for Siemens S5-95U PLC)The Operand Areas (for Siemens S5-95U PLC)

» I (Input)Interface from the process to the programmable controller

» Q (Output)Interface from programmable controller to the process

» 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 0.71.0 to 1.72.0 to 2.73.0 to 3.7

Output (Q) 4.0 to 4.7

5.0 to 5.7

8.0 to 8.7

9.0 to 9.7Counters (C) 0 to 63Timers (T) 0 to 127



Programming Basic Programming Basic FunctionsFunctions

Programming Basic Programming Basic FunctionsFunctions

Handout section 3.0

The Stages of Project PlanningThe Stages of Project PlanningThe Stages of Project PlanningThe Stages of Project Planning

Description of the Problem

Assignment Lists

Rough Structure of the Control System

Program Structure

Detailed Structure of the Control System

Handout section 3.1


Problem Description» it consists of process schematic, a short description of the task

definition, and a list of the sensors and actuators

Assignment 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


Rough Structure of the Control System» it contains all sub-functions of the process with relevant sensors,

actuators and indicators

Program 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

STL

A I 0.0A I 0.1= Q 4.0

&I 0.0

I 0.1Q 4.0

FBD

Programming AND OperationProgramming AND OperationProgramming AND OperationProgramming AND Operation

( )I 0.0 I 0.1 Q 4.0

LAD

Handout section 3.2

STL

O I 0.0O I 0. 1= Q 4.0

>= 1

FBD

I 0.0

I 0.1Q 4.0

OR OperationOR OperationOR OperationOR Operation

Handout section 3.3

LAD

( )I 0.0

I 0.1

Q 4.0

STLA I 0.0A I 0.1OA I 0.2A I 0.3= Q 4.0

AND - before - OR OperationAND - before - OR OperationAND - before - OR OperationAND - before - OR Operation

Handout section 3.4

( )I 0.0 I 0.1

I 0.2 I 0.3

Q 4.0LAD

I 0.0

I 0.1

I 0.2

I 0.3

I 0.0

I 0.1

I 0.2

I 0.3

Q 4.0

FBD

>= 1

&

&

STLA (O I 0.0O I 0.2)A (O I 0.1O I 0.3)= Q 4.0

OR - before - AND OperationOR - before - AND OperationOR - before - AND OperationOR - before - AND Operation

Handout section 3.5

( )I 0.0 I 0.1

I 0.2 I 0.3

Q 4.0LAD

I 0.0

I 0.1

I 0.2

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 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

SET Priority / Dominant SET RESET Priority / Dominant RESET

S1

S2

K1

K1

S3

S4

K2

K2

RS Memory FunctionRS Memory FunctionRS Memory FunctionRS Memory Function

Handout section 3.8

SET Priority / Dominant SET

=R

S Q

S1

S2

( )K1

S3

S4

K2

K2

RS Memory FunctionRS Memory FunctionRS Memory FunctionRS Memory Function

RESET Priority / Dominant RESET

=S

R Q

S4

S3

( )K2

S1

S2

K1

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 0.2 and I 0.3 ?

» I 0.4 and I 0.5 ?

( )I 0.0 I 0.1 Q 4.0

LAD

( )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 0.4 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”



so, Q 4.0 = “0”

( )I 0.0 I 0.1 Q 4.0

LAD

( )I 0.2 I 0.3 Q 4.0

( )I 0.4 I 0.5 Q 4.0





so, Q 4.0 = “0”

( )I 0.0 I 0.1 Q 4.0

LAD

( )I 0.2 I 0.3 Q 4.0

( )I 0.4 I 0.5 Q 4.0





this time, Q 4.0 = “1”

( )I 0.0 I 0.1 Q 4.0

LAD

( )I 0.2 I 0.3 Q 4.0

( )I 0.4 I 0.5 Q 4.0

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 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

( )M 100.0 Q 4.0

M 100.1

M 100.2

RLO STATA Q 4.0 …… ……A ( …… …… O I 0.1 …… …… O I 0.2 …… …… O I 0.3 …… …… )= Q 5.0 …… ……

Result of Logic Operation (RLO)Result of Logic Operation (RLO)Result of Logic Operation (RLO)Result of Logic Operation (RLO)

>=1

Q 4.0

I 0.0I 0.1I 0.2

Q 5.0&

Mathematics Logic Operation

Multiplication Before Addition

4 X 8 + 3 X 2 = 38AND before OR

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

Parenthesized FunctionParenthesized FunctionParenthesized FunctionParenthesized Function

Addition Before Multiplication

4 X (8 + 3 ) X 2 = 88

Parenthesized FunctionParenthesized FunctionParenthesized FunctionParenthesized Function

Mathematics Logic Operation

OR before AND

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


Numerical Systems and Numerical Systems and Data FormatsData Formats

Numerical Systems and Numerical Systems and Data FormatsData Formats

Handout section 4.0

Comparison of Number SystemsComparison of Number SystemsComparison of Number SystemsComparison of Number Systems

Handout section 4.1

Bit, Byte and Word AddressesBit, Byte and Word AddressesBit, Byte and Word AddressesBit, Byte and Word Addresses

Handout section 4.2

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

Functions:» Exchange information between various operand areas» Prepare times and counts for further processing» Load constants for program processing

Handout section 4.4

Load OperationLoad OperationLoad OperationLoad Operation

Byte d Byte c Byte b Byte a

0 IB 0Byte b Byte a

0 IB 10 IB 0

PII

IB 0

IB 1

L IB 0L IB 1

Information from PII

ACCUM 2 ACCUM 1

Transfer OperationTransfer OperationTransfer OperationTransfer Operation

Byte d Byte c Byte b Byte a

Byte d Byte c

PIQ

Byte a QB 0

T QB 0

Information in the PIQ

ACCUM 2 ACCUM 1

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


Timer OperationsTimer OperationsTimer OperationsTimer Operations

Handout section 5.0

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


Types of Timer - Pulse Timer (SP)Types of Timer - Pulse Timer (SP)Types of Timer - Pulse Timer (SP)Types of Timer - Pulse Timer (SP)


Extended Pulse Timer (SE)Extended Pulse Timer (SE)Extended Pulse Timer (SE)Extended Pulse Timer (SE)


On Delay Timer (SD)On Delay Timer (SD)On Delay Timer (SD)On Delay Timer (SD)


Stored On Delay Timer (SS)Stored On Delay Timer (SS)Stored On Delay Timer (SS)Stored On Delay Timer (SS)


Off Delay Timer (SF)Off Delay Timer (SF)Off Delay Timer (SF)Off Delay Timer (SF)

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)» 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

Handout section 5.4

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 0.0:JC FC 2::BEU::JU FC3:BE

::A I 0.6:BEC::BE

:::BE

:::BE

OB1

FC1

FC2

FC3

is always executed

is executed only when I 0.6 = “0”

is executed only when I 0.0 = “1”

is not executed

is not executed

System


Counter OperationsCounter OperationsCounter OperationsCounter Operations

Handout section 6.0

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 6.2

Timing DiagramTiming DiagramTiming DiagramTiming Diagram

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:

» Comparison satisfied RLO = “1”

» Comparison not satisfied RLO = “0”

Handout section 6.4

ComparatorComparatorComparatorComparator

introduction to plc (s7)

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