PLCs have become a pinnacle aspect of industrial automation, often serving as a link between machines and humans. As universal controllers, PLCs can be programmed to perform a variety of tasks, from pneumatic operations to mathematical computing. With the processing power, data storage, and communication capabilities of modern computers, PLCs provide a whole other level of application controls. PLCs are designed to deliver reliable operations in some of the most challenging situations, such as in high temperatures, electrical noise, shock, and vibration impact.
PLCs interact through direct connection with input and output equipment. Signals from sensors, switches, and other control devices provide external physical data about the PLC’s ambient operations. PLCs were designed through ladder logic, but modern PLCs are not solely limited to ladder logic, and PLC outputs provide feedback to determine the best possible decision to change the process or environment.
PLC implementation offers numerous performance benefits, such as reduced hardware requirements, increased efficiencies, and less product waste. Modern PLCs are highly customizable and can be designed to individual control applications while greatly reducing production floor usage.
With built in controllers, PLCs make installation easier because it needs less space. Also, PLC displays improve operator interaction which leads to increase production efficiency.
Maintenance and troubleshooting, repairs are reduced due to plug-in components and replacing modules. The chances of PLC faults and the time required to fix errors is significantly reduced, which leads to complete elimination of rewiring of relay panels and accessory components. Additionally, fault detection circuits and diagnostic indicator integration in major components can monitor if components are functioning properly.
A programmable logic controller is a special computer that controls machines and processes. It therefore shares a common ground with PCs like central processing unit, memory, software, and communications. Unlike PCs the PLC is designed to survive in harsher industrial environments and are very flexible in its interfacing with inputs and outputs.
PLCs are typically have the following components:
PLCs come in many different shapes and sizes. Some can fit into your pocket, while larger control systems require large PLC racks.
The input/output system works in tandem with the CPU. Where the input devices record and measure the data received by the monitoring components and provides information for the CPU to determine what the machine or process should do with it. The output system relays the execution of the program from the CPU into the operating machines and processes. Usually the PLC executes a single type of execution for a specific task or process. This allows the system to automate the task based on the PLCs feedback sensors.
With PLC design and development reaching new heights every year, the potential industrial applications continue to grow. Here are a few of the industries that use PLCs and the applications for them.
Snack Food Industry
Material Conveying
Building Products
Pharmaceuticals
Steel Industry
Packaging and Labeling
Its basic, but understanding application requirements will help determine if PLCs are best for your automation system. Typical factory automation applications, which PLCs were designed for, involve the manufacturing/assembling of specific items. These applications involve one or more machines and a large amount of material movement. Typically these types of processes are monitored by an operator that watches the progression through the manufacturing line. These processes are highly logic controller and require high-speed requirements. This is often controlled by PLCs and Human Machine Interface (HMI) combination.
If product value is relatively low, and/or downtime results in lost production, but with little additional cost or damage to the process, the PLC is a good choice. For on-demand product manufacturing, where manufacturing is non-continuous, which a company is allowed proper shutdowns for maintenance, troubleshooting, or upgrades having little impact on production screams the PLC application.
Typically in a PLC environment the operator primarily handles exceptions. Status information and alarming aids the operator in staying aware of what the process is doing. This is essential the definition of “Lights Out Manufacturing”. If an operator is needed only to supervise then a PLC system might be for you.
PLCs are designed for high-speed applications that require high scan rates involving motion control, high-speed interlocking, or control of motors and drives. Fast scan rates are necessary to be fully effective in controlling these devices. Which make them great for the on-demand product market.
PLCs were designed as the customizable king. The development of customized routines and functions is required to satisfy unique application needs. A systems integrator can switch from one type of manufacturing machine today and switch over to using it in a completely different system tomorrow. This is the power of programmable logic controls and their ability to switch from one application to another by rewriting the code.
Factory industrial automation engineers want customizable platforms where individual components can be reprogrammed to accomplish the desired task. Integrators and engineers breakout the PLCs and begin programming based on what they need. The tools provided by PLCs typically support a “bottoms-up” approach to engineering, which works wonders for smaller applications.
PLCs have earned their right in automation industries with their high-speed production rate and system flexibility. They have been around for a long time now, but they are still developing into a power tools for any industrial application. Next week we will go into how to properly select a PLC for your application and understanding PLC documentation.
Would a PLC help out you facility? Let us know what you are looking to automate in the comments down below.