Before discussing or understanding the Programmable Logic Controller, we must first understand the devices the PLC was invented to replace. That was the ladder diagram. The ladder diagram or electrical schematic or elementary diagram can be divided into two distinct portions.
The first is the power portion and the second is the control. Showing flow of power to motor or other device in a factory environment is the primary focus of the power portion.Showing control of that motor is the focus of the control portion. While power flow is important, the focus is to dissect the control portion. Items such as fuses and disconnect devices may appear in both power and control circuits. The use of symbols is important for both power and control. The types of symbols vary and are somewhat arbitrary based on where you are located and, in some cases, the company you work for. This is contrary to the symbols used in the PLC which must be fixed or uniform. The use of symbols is a descriptive description of the device being used.
This user’s manual describes basic and advanced instructions and the usage of software for SmartAXIS ladder programming.
Chapter 1: Operation Basics General information about simple operating procedures from creating a user program using WindLDR on a computer to monitoring the SmartAXIS operation.
Chapter 2: Ladder Program Monitoring on the SmartAXIS Monitoring the ladder program in the SmartAXIS.
Chapter 3: Device Addresses Device addresses available for the SmartAXIS to program basic and advanced instructions. Special internal relays and special data registers are also described.
Chapter 4: Instructions Reference List of all basic and advanced instructions and general rules of using advanced instructions, terms, data types, and formats used for advanced instructions.
Chapter 5: Basic Instructions Programming of the basic instructions, available devices, and sample programs.
Chapter 6 through Chapter 26: Detailed descriptions for advanced instructions.