Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

19.5.1 IEC 1131

 

· The IEC 1131 standard is an effort towards standardizing PLC oriented control. This is more necessary now that personal computers and software are starting to open the PLC market.

 

· These standards were not designed to force a rigid style, so the different PLC vendors will still have programming environments that vary, but the conceptual elements will be consistent.

 

· The most notable differences between implementation of PLCs will be addresses of outputs, inputs, internal memory, etc.

 

· There are a few components to the standard,

  1. IEC 1131-3 Data types and programming
  2. IEC 1131-5 Communications
  3. IEC 1131-7 Fuzzy control

 

· IEC 1131-3 defines the basic programming languages,

  1. IL (Instruction List) - This is effectively mnemonic programming
  2. ST (Structured Text) - A BASIC like programming language
  3. LD (Ladder Diagram ) - Relay logic diagram based programming
  4. FBD (Function Block Diagram) - A graphical dataflow programming method
  5. SFC (Sequential Function Charts) - A graphical method for structuring programs

 

· Many of the functions described in this note set support the standard.

 

· The standard also defines data types,