Human machine interface (HMI) software gives machine operators a way to interact with and manage a system. This interaction is through a graphical user interface (GUI), which facilitates information exchange and communication between two types of HMIs; a supervisory level and a machine level. Generally, HMI software is designed for either machine level HMI or supervisory level HMI, with applications suitable for both types. These software applications are expensive at the outset, but can lower long-term costs and reduce redundancies in the long run.
Selecting HMI software typically starts with an analysis of product specifications and features. The key considerations can include the system architecture, performance requirements, integration and cost of procurement and operations.
The HMI system typically presents the information to the operator through some sort of GUI. More advanced HMI systems allow operators to view diagrams, digital photos and detailed system schematics. For motion control applications, the visual GUI can range from simple 4 line x 20 column text displays to color monitors with touchscreen controls. HMI display screens come in standard, advanced, compact and high performance versions. The latter can be customized based on the operator’s requirements. The standard version is normally used on low-cost systems that are not task-intensive.
Sometimes, an HMI unit can be programmed to perform some basic control functions as well, such as editing servomotor parameters and even issuing global commands to other control axes on a machine. This places them well beyond a basic type of HMI with only simple functions such as observing processes or making very simple changes to some individual variables or parameters or setpoints.
HMI software editors are available to provide touch screen functionality through a multitude of dimensions and colors. Additionally, they offer control functions for industrial automation machines. Programming can be done using Windows-based and screen editor software. It can permit quick editing of schematics and set suitable communication protocols.
HMI accessories complement the displays based on the requirements of the operator. Depending on the complexity of the application, there are a range of I/O options available such as the number of digital or analog inputs or outputs, and communication protocols range from simple RS-232 links to more advanced protocols such as CANOpen, SERCOS, and Ethernet-based communications.
Communications on multiple networks are supported through ControlNet and DeviceNet. ControlNet is a control-level network that provides high-speed transmission of time-critical messaging data and I/O data. DeviceNet handles industrial devices like drives, limit switches, motor starters, operator displays, photoelectric cells, and valve manifolds to personal computers (PC) and programmable logic controllers (PLC). The use of both communication systems provides HMI software data management between the machines and operator interactions.
More sophisticated HMI software is structured around mobile, portable platforms such as the Microsoft Windows CE platform, a scalable version of the Windows operating system for handheld devices. This presents a cost-saving value as the operating systems are distributed on machine-level embedded HMI, solid-state open HMI machines, distributed HMI servers and portable HMI devices.
Content provided by Design World.