The purpose of having an automated process is to enhance process operations based on safety, performance, process improvements, availability, repeatability, and other relevant factors. Human-machine interfaces (HMIs), the primary means by which users interact with a process, provide the potential and opportunity both to greatly facilitate and enhance operations or to otherwise confuse users and degrade operations.
ISA's first human-machine interface (HMI) standard, ANSI/ISA-101.01-2015, Human Machine Interfaces for Process Automation Systems, covers the philosophy, design, implementation, operation, and maintenance of HMIs for process automation systems, including multiple work processes throughout the HMI life cycle. It defines the terminology and models to develop an HMI and the work processes recommended to effectively maintain the HMI throughout the HMI life cycle, including all general concepts until its decommissioning, applying a practical and management approach. The target audiences include end users, designers, developers, and implementers of HMI systems.
In addressing HMIs for equipment and automated processes, the ISA-101 standard provides information, guidelines and a methodology to enable users to be more effective in yielding improved safety, quality, production, and reliability. The practices in the standard are applicable to continuous, batch, and discrete processes, and indeed to any process using an HMI for interfacing to a controlled system. There may be differences in implementation to meet the specific needs based on process type.
The ISA101 standards committee has now published the first in a series of technical reports to provide further guidance in key areas of HMI. ISA-TR101.02-2019, HMI Usability and Performance, addresses the specification, design, implementation details, and management of an HMI focused on usability and performance. It explains how the ISA-101 standard applies in determining the optimal solution to achieve the process goals using examples that have been shown to be effective.
HMI enhancements for improved usability and performance are often associated with additional specifications, custom design, implementation, and management considerations, in addition to vendor-provided functionality and features. The new technical report includes examples of these considerations within the HMI life cycle, including the continuous work processes of audit, validation, and management of change. The technical report was written with due consideration to other guidance documents that have been developed throughout industry.
The ISA101 committee is currently working on additional technical reports in three areas. The first area is directed at describing the guiding principles and conceptual foundations as a basis for implementation of the HMI, including but not limited to HMI philosophy and an HMI style guide. This technical report will describe general example applications of the philosophy and style guide and will be both target-platform and implementation independent.
The second area is focused on mobile devices, such as tablets and smartphones. This technical report will describe the potential applicability of the ISA-101 standard to mobile applications and devices as process automation HMI, including but not limited to:
- life-cycle process differences versus what is included in the current ISA-101 standard
- HMI design considerations for process control
- user interaction and collaboration considerations
- functional safety and availability of the mobile HMI
- mobile device selection appropriate for the operating environment.
HMI graphical requirements for on-machine applications are very different from those for process industries and control room use. While the ISA-101 standard is effective in guiding developers and end users on how to optimize graphics in an HMI application for process-based industries, it does not reflect the needs of original equipment manufacturers and machine builders.
Accordingly, a third area of work within ISA101 is directed at developing a technical report that will have recommended practices and examples for the application of the ISA-101 standard to on-machine applications, focused on developing HMI graphics that effectively convey contextual information for operating and maintaining a machine.
For example, "set up" is a prime activity in which an effective HMI application can decrease the time needed to set up a machine between different products by guiding an operator through the process; and proximity and line-of-sight security are just two ways an HMI can more effectively guide an operator or provide the relevant information an operator needs for the operator's particular position in regards to a machine and its current state.
ISA101 is co-chaired by Maurice Wilkins of Yokogawa and Greg Lehmann of AECOM. For information on ISA101, contact Charley Robinson, ISA Standards, firstname.lastname@example.org. For information on viewing or obtaining the ISA-62443 standards and technical reports, visit www.isa.org/findstandards.
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