NEMA IA 2.8:2005

FOREWORD
INTRODUCTION
1 General
  1.1 Scope
  1.2 Normative references
  1.3 Abbreviated terms
  1.4 Overview
2 Introduction to IEC 61131-3
  2.1 General considerations
  2.2 Overcoming historical limitations
  2.3 Basic features in IEC 61131-3
  2.4 New features in the second edition of IEC 61131-3
  2.5 Software engineering considerations
       2.5.1 Application of software engineering principles
       2.5.2 Portability
3 Application guidelines
  3.1 Use of data types
       3.1.1 Type versus variable initialization
       3.1.2 Use of enumerated and subrange types
       3.1.3 Use of BCD data
       3.1.4 Use of REAL data types
       3.1.5 Use of character string data types
       3.1.6 Use of time data types
       3.1.7 Declaration and use of multi-element variables
       3.1.8 Use of bit-string functions
       3.1.9 Strongly typed assignment
  3.2 Data passing
       3.2.1 Global and external variables
       3.2.2 In-out (VAR_IN_OUT) variables
       3.2.3 Formal and non-formal invocations and argument
              lists
  3.3 Use of function blocks
       3.3.1 Function block types and instances
       3.3.2 Scope of data within function blocks
       3.3.3 Function block access and invocation
  3.4 Differences between function block instances and
       functions
  3.5 Use of indirectly referenced function block instances
       3.5.1 Establishing an indirect function block instance
              reference
       3.5.2 Access to indirectly referenced function block
              instances
       3.5.3 Invocation of indirectly referenced function
              block instances
       3.5.4 Recursion of indirectly referenced function
              block instances
       3.5.5 Execution control of indirectly referenced
              function block instances
       3.5.6 Use of indirectly referenced function block
              instances in functions
  3.6 Recursion within programmable controller programming
       languages
  3.7 Single and multiple invocation
  3.8 Language specific features
       3.8.1 Edge-triggered functionality
       3.8.2 Use of EN/ENO in functions and function blocks
       3.8.3 Use of non-IEC 61131-3 languages
  3.9 Use of SFC elements
       3.9.1 Action control
       3.9.2 Boolean actions
       3.9.3 Non-SFC actions
       3.9.4 SFC actions
       3.9.5 SFC function blocks
       3.9.6 'Indicator' variables
  3.10 Scheduling, concurrency, and synchronization mechanisms
       3.10.1 Operating system issues
       3.10.2 Task scheduling
       3.10.3 Semaphores
       3.10.4 Messaging
       3.10.5 Time stamping
  3.11 Communication facilities in ISO/IEC 9506/5 and IEC 61131-5
       3.11.1 Communication channels
       3.11.2 Reading and writing variables
       3.11.3 Communication function blocks
  3.12 Deprecated programming practices
       3.12.1 Global variables
       3.12.2 Jumps in FBD language
       3.12.3 Multiple invocations of function block instances in
              FBD
       3.12.4 Coupling of SFC networks
       3.12.5 Dynamic modification of task priorities
       3.12.6 Execution control of function block instances by
              tasks
       3.12.7 Incorrect use of WHILE and REPEAT constructs
  3.13 Use of TRUNC and REAL_TO_INT functions
4 Implementation guidelines
  4.1 Resource allocation
  4.2 Implementation of data types
       4.2.1 REAL and LREAL data types
       4.2.2 Bit strings
       4.2.3 Character strings
       4.2.4 Time data types
       4.2.5 Multi-element variables
  4.3 Execution of functions and function blocks
       4.3.1 Functions
       4.3.2 Function blocks
  4.4 Implementation of SFCs
       4.4.1 General considerations
       4.4.2 SFC evolution
  4.5 Task scheduling
       4.5.1 Classification of tasks
       4.5.2 Task priorities
  4.6 Error handling
       4.6.1 Error-handling mechanisms
       4.6.2 Run-time error-handling procedures
  4.7 System interface
  4.8 Compliance
       4.8.1 Compliance statement
       4.8.2 Controller instruction sets
       4.8.3 Compliance testing
5 PSE requirements
  5.1 User interface
  5.2 Programming of programs, functions and function blocks
  5.3 Application design and configuration
  5.4 Separate compilation
  5.5 Separation of interface and body
       5.5.1 Invocation of a function from a programming unit
       5.5.2 Declaration and invocation of a function block
              instance
  5.6 Linking of configuration elements with programs
  5.7 Library management
  5.8 Analysis tools
       5.8.1 Simulation and debugging
       5.8.2 Performance estimation
       5.8.3 Feedback loop analysis
       5.8.4 SFC analysis
  5.9 Documentation requirements
  5.10 Security of data and programs
  5.11 On-line facilities
Annex A (informative) Changes to IEC 61131-3, Second edition
Annex B (informative) Software quality measures
Annex C (informative) Relationships to other standards
INDEX
Bibliography

Specifies communication aspects of a PLC. This Standards publication is a NEMA Adoptive Standard based on Part 5 of IEC 61131.