What are PLCs and how do they work?
Programmable logic controllers (PLCs) are thought of as the digital brain of automated systems as it is a solid state device that is able to receive input signals, process, analyse and transmit output data to control a large number of devices to apply logic to tasks to ensure they perform at optimum levels.
What are HMIs?
A Human Machine Interface (HMI) allows real-time process information to be presented to a human user, to be able to control and modify the process.
What is a SCADA system?
Supervisory control and data acquisition (SCADA), is the term used to describe a full industrial control system that uses a computer system to monitor and control a process. This is where PLCs and HMIs work together. A system will usually comprise:
- A HMI - To present data to a human operator
- Supervisory (computer) system - To gather data sending commands
- Remote Terminal Units (RTUs) - To connect sensors
- PLCs - To apply logic to devices in the process
- Communication infrastructure - To provide connectivity
- Food and beverage
- Automobile
- Manufacturing
- Bottling
- Easy to re-programme even whilst a system is running
- Highly reliable
- Fast issue diagnosis
- Access to data
- Complex logic achievable without difficult wiring
- Utilise panel space effectively
What industries are both HMI and PLCs used in?
All automated systems can rely on and benefit from process control devicesl. Some key industries they are used in are:
What advantages does process control hardware deliver?
Here are some benefits of using PLCs and HMIs over traditional wiring methods:
How do you select a PLC?
They're usually available as a fixed configuration or in modular format. The specific model required is highly dependent on the application, the software package, the environment it will be used in and networking capabilities. There are some key points to consider such as the number of input and output points. A simple rule to follow is the larger the systems, the larger the memory, programming, and communication capabilities.
