17INSTRUCTION LIST PROGRAMMING

Topics:

• Instruction list (IL) opcodes and operations

• Converting from ladder logic to IL

• Stack oriented instruction delay

• The Allen Bradley version of IL

Note: Allen Bradley does not offer IL programming as a standard option so this chapter may be considered optional.

Objectives:

• Instruction list (IL) opcodes and operations

• Converting from ladder logic to IL

• Stack oriented instruction delay

• The Allen Bradley version of IL

Instruction list (IL) programming is defined as part of the IEC 61131 standard. It uses very simple instructions similar to the original mnemonic programming languages developed for PLCs. (Note: some readers will recognize the similarity to assembly language programming.) It is the most fundamental level of programming language - all other programming languages can be converted to IL programs. Most programmers do not use IL programming on a daily basis, unless they are using hand held programmers.

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