iec 61131 basics
TRANSCRIPT
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IEC 61131 BasicsPresented by
Bill Lydon, Director PLCopen North AmericaAutomation Industry Consultant
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Why standard software?
Standardization Improves Productivity
Quality & Reliability
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Percentage of Software development costs in production systems (source: McKinsey)
0%
20%
40%
60%
80%
100%
1970 1980 1990 2000
Mechanic Electric Software
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Software Functions IncreasingComplexity Increases Exponentially
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“… the never ending story of software ”enhancements…..
new requirements ...new functionalities ….
new wishes ...
Typically software enhancements & maintenance cost are 2 times the initial development investment.
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ConceptualDesign Specification
FunctionalDesign
Verification
CodingTesting
Refining
Commissioning
Maintenance
Standard Software Advantages
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for efficiency in automationStandard Software Advantages Improved Software Reliability – Common Design
Architecture Improved Productivity Common Base of Understanding & Training Improves Maintenance Efficiency
• Emergency Bug Fixes & Corrective Bug Fixes• Adding Features & Functions• Mandatory Changes ( Law, Safety,...)• Enhancements• Studies show software maintainers spend about 50% their time
understanding the code.
Lifecycle Maintenance = 2 X Initial Development
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IEC 61131-3 - International Electrotechnical Commission (IEC)Open Programmable Logic Controller Standard
1st published 1993 - 3rd edition published 2013
Defined application program development environment Strong data typing for error prevention 1 Structuring Tool – Sequential Function Chart (SFC) 4 programming languages: 2 Textual & 2 Graphical Program Organization - Program Structuring & Reuse
What is IEC 61131-3 ?
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IEC 61131-3 Strong Data Types
BOOLEAN REAL INTEGER STRING
TIME ARRAY STRUCTURES USER DEFINED
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Languages Instruction List (IL) Structured Text (ST) Ladder Logic/Diagram (LD) Function Block (FB) Sequential Function Chart (SFC)
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A B C-| |--|/|----------------( )---[Function[---
Ladder Diagram (LD)
Standardized set of relay ladder programming symbols and terminology
• Electrical Flow• Large base of users• Boolean equations• Function Blocks• Easy rules
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for efficiency in automationLadder Diagram (LD)
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LD AAND BST C
• Single accumulator based execution model
• Low Level Programming
• One operation such as storing a value in the accumulator register, is allowed per line
Instruction List (IL)Single statements, or instructions, written and executed in a line-by-line format.
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for efficiency in automationInstruction List (IL)
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C:= A AND NOT BIf A = FALSE THEN ...CASE Select OF ....
• High level language, block structured• Syntax resembles PASCAL, C, C+• Complex statements and nested instructions
possible• Support for
• Iteration loops (REPEAT-UNTIL; WHILE-DO)• Conditional execution (IF-THEN-ELSE; CASE)• Functions (SQURT(); SIN())
Structured Text (ST)
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for efficiency in automationStructured Text (ST)
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ANDA CB
• Graphical Language
• Program elements appear as blocks to be “wired” together
Function Block Diagram (FB)
Function Examples: ADD, SQRT, SIN, COS, AND, OR, CASE, etc.
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for efficiency in automationFunction Block Diagram (FB)
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Inputs Outputs
Function Block• Explicit Data• Variables• Tag Names• Logic• Actions/Calculations
Self Contained Building Blocks
Function Block
Inherent Data Integrity Checks
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Inputs Outputs
Function Examples• AND, OR, XOR, GATE…• PID, SELECT, LIMIT…• SQUARE ROOT, COS…• ADD, SUB, DIV, MUL…
Function Block
Self Contained Building Blocks
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for efficiency in automationFunction Block
Inputs Outputs
Send/Receive EmailServe UP WEB PagesSend Messages (SMS)Send SOAP MessagesSend XML MessagesOPC UA CommunicationPEER to PEER
Self Contained Building Blocks
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BUILDYOUR OWNFUNCTIONS
Function Block
Encapsulation
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for efficiency in automationFunction Block
Built from standard blocks ...
Inputs OutputsUser Created
Object
Encapsulation
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for efficiency in automationFunction BlockLadder Logic Instruction List Structured Text
Build your own function blocks with Ladder Logic, Instruction List, or Structured Text Standardization
Reuse Tested CodeEasily UnderstoodSelf DocumentingPassword Protect
Inputs OutputsYour OwnFunction Block
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for efficiency in automationSequential Function Chart (SFC)
Step 1
Transition
Step 2
Transition
Action 1Action 2
Action 1
• Sequential Controls• Procedural Controls• Structured • Describes Process• Logic Driven • Partition Control Functions• Rapid Visual Diagnostics
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• Serial & Parallel Processes• Process Synchronization• Application examples
• Startup Sequences• Shutdown Sequences• Presses• Productions Lines• Process Automation• Packaging technology• Machine tools • Batch Process Control – S88• Flexible Manufacturing
Sequential Function Chart (SFC)
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• Multiple Automation and Control Disciplines• Process Design• Logic Simulation• Automatic Documentation• Engineering Tools
• Online Debug Environment• Breakpoints• Watch Windows• Strip chart Recorder• Integrated HMI
IDE - Integrated Design Environment (IDE)
IEC 61131 Controller
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for efficiency in automationPLCopen Extensions Vendor Independent, Not for Profit Organization Extends IEC 61131-3 Functionality
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More Information...www.PLCopen.org
Electronic NewsletterApplication Examples
SpecificationsCompliant Products
Bill Lydon, Director PLCopen North AmericaAutomation Industry Consultant
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