ISPSoft User Manual 12.1 Introduction of Instruction Lists An instruction list is one of the five languages supported by the IEC 61131-3 standard. It is a low level language and resembles an assembly language. In earlier times, users entered control instructions into a PLC through a programming panel, and the programming language used was an instruction list. 12.1.1 Structure of an Instruction List accomplished by a complete ladder diagram can be accomplished by an instruction list composed of many An instruction list is composed of statements. Every statement represents an action. A task which can be instructions. An example of an instruction list is shown below.
There are five lines of program code. The ladder diagram corresponding to the instruction list is shown at the right side of the instruction list. Every statement on an instruction list is composed of an operator and operands. An operator is a function representing an operation, and an operand is the object of an operation. An operand can be a device, a symbol, 12-2 LD M0: Loading the state of M0 OR M1: The logical OR operation is performed on M1. AND M2: The logical AND operation is performed on M2. OUT M3: M3 The result of the operation is sent to M3. (*Note*): It is a comment on the program. When the program is compiled, this line is skipped automatically. No action