Question

Which of the following is NOT one of the most common language structures of PLC programming?
1. Forward language 
2. Ladder diagram 
3. Boolean language
4. Function chart

Answer 1

Correct Answer - Option 1 : Forward language 

Different Programming languages identified for PLC are:

1. Ladder diagrams (LAD)
2. Instruction list (IL)
3. Sequential function charts (SFC)
4. Structured text (ST)
5. Function block diagrams or charts (FBD)
    

Ladder diagrams (LAD):

• It is visual programming language is a PLC programming language called ladder logic or ladder diagram (LD).
• It is a graphical PLC programming language that expresses binary logic operations with symbolic notation using ladder diagrams.
   

Instruction list (IL):

• Instruction lists (or ILs) are one of the five PLC programming languages defined by the IEC 61131-3 standard.
• ILs are not graphical programming languages. Instead, they most resemble assembly language programming.
• It comes along with the Ladder Logic.
   

Sequential function chart (SFC):

• It is a graphical programming language used for programmable logic controllers (PLCs).
• The SFC standard is defined as, Preparation of function charts for control systems, and was based on GRAFCET (itself based on binary Petri nets).
   

Structured text (ST or STX):

• It is one of the five languages supported by the IEC 61131-3 standard, designed for programmable logic controllers (PLCs).
• It is a high-level language that is block-structured and syntactically resembles Pascal, on which it is based.
   

Function block diagrams or chart (FBD):

• It widely used PLC programming language is the Function Block Diagram (FBD).
• It is a simple and graphical way to program any functions together in a PLC program.