PLC SCADA DCS Training in Chennai | Industrial Automation training Chennai,

PLC SCADA DCS Training in Chennai | Industrial Automation training Chennai,

What is an HMI?

HMI is the acronym for Human Machine Interface, and can be designed as just that; an interface between the user and the machine. An HMI is considered an interface; a very broad term that can include MP3 players, industrial computers, household appliances, and office equipment. However, an HMI is much more specific to manufacturing and process control systems. An HMI provides a visual representation of a control system and provides real time data acquisition. An HMI can increase productivity by having a centralized control center that is extremely user-friendly. 

HMI Block Diagram;

A Human Machine Interface (HMI) is exactly what the name implies; a graphical interface that allows humans and machines to interact. Human machine interfaces vary widely, from control panels for nuclear power plants, to the screen on an iPhone. However, for this discussion we are referring to an HMI control panel for manufacturing-type processes. An HMI is the centralized control unit for manufacturing lines, equipped with Data Recipes, event logging, video feed, and event triggering, so that one may access the system at any moment for any purpose. For a manufacturing line to be integrated with an HMI, it must first be working with a Programmable Logic Controller (PLC). It is the PLC that takes the information from the sensors, and transforms it to Boolean algebra, so the HMI can decipher and make decisions.

Basic Types of HMIs :

There are three basic types of HMIs: the pushbutton replacer, the data handler, and the overseer. Before the HMI came into existence, a control might consist of hundreds of pushbuttons and LEDs performing different operations. The pushbutton replacer HMI has streamlined manufacturing processes, centralizing all the functions of each button into one location. The data handler is perfect for applications requiring constant feedback from the system, or printouts of the production reports. With the data handler, you must ensure the HMI screen is big enough for such things as graphs, visual representations and production summaries. The data handler includes such functions as recipes, data trending, data logging and alarm handling/logging. Finally, anytime an application involves SCADA or MES, an overseer HMI is extremely beneficial. The overseer HMI will most likely need to run Windows, and have several Ethernet ports. 

How to Select an HMI :

An HMI is a substantial purchase, so it is important to know exactly what is required of it. An HMI is used for three primary roles: a pushbutton replacer, data handler, and overseer. The pushbutton replacer takes the place of LEDs, On/ Off buttons, switches or any mechanical device that performs a control function. The elimination of these mechanical devices is possible because the HMI can provide a visual representation of all these devices on its LCD screen, while performing all the same functions. The Data Handler is used for applications that require constant feedback and monitoring. Often these Data Handlers come equipped with large capacity memories. The last of the HMI three types is referred to as the overseer, because it works with SCADA and MES. These are centralized systems that monitor and control entire sites or complexes of large systems spread out over large areas. An HMI is usually linked to the SCADA system's databases and software programs, to provide trending, diagnostic data, and management information

Physical Properties of a HMI :

The actual physical properties of an HMI vary from model to model and among manufacturers. It is important that one makes the appropriate selection. An HMI that is located in a water plant might have various water seals around its perimeter, as opposed to an HMI that is located in a pharmaceutical warehouse. The actual size of an HMI is also a key physical property that will vary, because not all applications require a large, high-resolution monitor. Some applications may only require a small, black and white touch screen monitor. When it comes to selecting an HMI, the physical properties are extremely important because one must take into consideration the operating environment, and what safety measures the HMI needs to protect itself. Also, a specific size may be needed due to space limitations. Lastly, physical properties include the processor and memory of the HMI. It is important to make sure that the processor and memory capabilities are sufficient enough to control a system. 

How does an HMI Work?  

First consider the other components that are necessary to make a manufacturing control system operate. The production line consists of all the machinery that performs the work required in the production of the product. Next, consider the various input/output sensors that monitor temperature, speed, pressure, weight and feed rate. Third, decide on the programmable logic controller (PLC) that will receive the data from the input/output sensors, and converts the data into logical combinations.