Programmable Logic ControllersSlide 2AgendaIEC 61131 StandardProgramming ModelsInstruction ListInstruction List ExampleInstruction List Example 2Structured TextSlide 10Ladder DiagramSlide 12Function Block DiagramFunction Block Diagram ExampleSequential Function ChartsSequential Function Chart ExampleProgrammable Logic Programmable Logic ControllersControllersLecture 27Lecture 27PLC LanguagesPLC LanguagesJesus is a friend who knows all your faults and still loves you anyway.But God demonstrates his own love for us in this: While we were still sinners, Christ died for us. Romans 5:8AgendaAgendaIEC 61131 StandardProgramming ModelsInstruction ListStructured TextLadder DiagramFunction Block DiagramSequential Function ChartsIEC 61131 StandardIEC 61131 Standard•Common and open framework •Loosely defined•Approved in 1992•Six Main Components- IEC 61131-1 Overview- IEC 61131-2 Requirements and Test Procedures- IEC 61131-3 Data Types and Programming- IEC 61131-4 User Guidelines- IEC 61131-5 Communications- IEC 61131-7 Fuzzy ControlProgramming ModelsProgramming ModelsIL (Instruction List)ST (Structured Text)LD (Ladder Diagram)FBD (Function Block Diagram)SFC (Sequential Function Charts)Instruction ListInstruction List•Textual PLC Programming Language•Effectively Like Assembly Programming •Best Suited for Small Uncomplicated Programs•Instructions Consist of:- Operator- Modifier- OperandExample: AND NOT 00200Instruction List ExampleInstruction List ExampleInstruction List Example 2Instruction List Example 2Structured TextStructured Text• Textual PLC programming language• Effectively like BASIC programming • Easiest to troubleshoot and understand• Useful for implementing calculation-intensive functions and other difficult functions• Instructions consist of constructs•Example: Analog_Out := Error * Gain;Structured TextStructured Text * Sample Structured Text Code * (comments)VAR (variables)temp: INT;error: BOOL;END_VARtemp := %IW4; (addresses)IF temp > 3200 THEN error := TRUE;%QW := 200;ELSE%QW := temp / 16;END_IF;Ladder DiagramLadder Diagram• Primary programming language• Resembles original relay logic documentation• Addressing and memory is different for every manufacturer• Ladder logic scanning (rung order vs. network column)• Not purely parallel processor like relay logicLadder DiagramLadder DiagramFunction Block DiagramFunction Block Diagram• Graphical data-flow programming method• Interconnected blocks• Similar to Ladder LogicFunction Block Diagram ExampleFunction Block Diagram ExampleSequential Function ChartsSequential Function Charts• Graphical method for structuring programs• Design tool for sequential problems•Consists of:- Interconnected steps- Actions- TransitionsSequential Function Chart Sequential Function Chart