SIMPLE PROGRAM DIAGRAMS ARCHITECTURE SOFTWARE

When considering PLC architecture types we can generally say that fixed PLCs are used for smaller sized, less complex application. There is also crossover between PLC types with some fixed type PLCs having modular type features and some modular type PLCs having distributed type features. The terminology surrounding PLC types can vary between PLC manufacturers, especially when talking about fixed PLCs. The 3 distinct types of PLC architecture available for use in industrial automation are known as fixed, modular and distributed. Today the options and variations available to the traditional PLC architecture types is almost endless between different PLC manufacturers. PLC architecture has advanced tremendously since its inception of the PLC back in the 1960s. The power supply is responsible for supplying and managing the power requirements of the various PLC hardware components. The CPU also controls and exchanges data with the communication interface and devices.Īn addressing system is used for data organization that is shared between the various hardware components.Ī programming terminal is used to formulate the PLC program (eg ladder logic), load the program into the controller and monitor/control the PLC and its program.

The resulting data flows to the output interface for conditioning and execution of the output devices. Once all the data is gathered the program (eg ladder logic) is processed in a cyclic fashion. The CPU processor also exchanges data with the program and data memory. The block diagram below explains the basic architecture of a PLC….ĭata flow is from the input devices, through the CPU processor and then to the output devices. The CPU control unit manages the interaction between the various PLC hardware components while the CPU processor handles all the number crunching and program (eg ladder logic) execution. It is made up of a control unit and processor. The heart of the PLC system is the CPU (Central Processing Unit).

SIMPLE PROGRAM DIAGRAMS ARCHITECTURE SOFTWARE

However if a PLC system is described as having open architecture it refers to the PLC system as having off the shelf components that adhere to a common standard and are easily connected to other manufacturer’s hardware and software components. If a PLC system is described as having closed architecture it refers to a proprietary system of hardware and software components that cannot (or is difficult to) connect to other manufacturers components and software. However, PLC architecture does differ because the design is based around providing high reliability, immunity to harsh industrial environment, ease of maintenance and access to large amounts of peripheral inputs and outputs.

The architecture of a PLC is based on the same principles of that used in standard computer architecture. The term PLC architecture refers to the design specification of the various PLC hardware and software components and the how they interact with one another to form the overall PLC system.

In this article we’ll look at basic PLC architecture, the different types of PLCs used in industrial automation, advantages and disadvantages of PLC types and compare them in a handy reference table.

Simple program diagrams architecture