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HMIs – a new ISA standard looms

22 October 2014

A new standard on human-machine interfaces (HMIs) - ISA101 - will shortly be published. “We’ve had our ups and downs, but industry is really waiting for this,” says Maurice Wilkins, vice president of Yokogawa’s Global Strategic Marketing Center and co-chair of the ISA101 committee.

Originally known as the Instrument Society of America, the International Society of Automation (ISA) is a non-profit technical society for engineers and others who work and study in industrial automation.

Many ISA standards are used by automation professionals. An example is the ANSI/ISA-50.02 Fieldbus Standard for Use in Industrial Control Systems; ISA100.11a is for testing and certification of wireless products and systems, which was approved by the International Electrotechnical Commission (IEC) as a publicly available specification, or PAS, in September 2011.

Wilkins’ company Yokogawa has been developing ISA100 wireless-compliant technologies and devices, such as adapters that allow conventional wired devices to access wireless networks. Now, the company has signed an agreement for the distribution of ISA100 Wireless-based gas detectors from GasSecure AS, a company which specialises in wireless gas detectors that monitor for hydrocarbon leaks at offshore platforms, tank farms and industrial plants.

ISA101 standard on HMI

HMI links operators and automation systems. An HMI that is easy to understand and gives clear options to end users will produce fewer errors, increase operator productivity, and reduce stress.

IAS101 is aimed at those responsible for designing, implementing, using, or managing HMI applications. The standard defines both the terminology and models to develop an HMI and the work processes recommended to effectively maintain it throughout its life cycle. It should also improve the user's abilities to detect, diagnose, and properly respond to abnormal situations.

Yokogawa’s CENTUM VP R5.04 integrated production control system (Fig 2) has enhanced alarm and batch functions and is typical of the type of equipment at which the new standard is targeted. A prominently coloured tag mark is displayed on the HMI screen next to any measurement reading that falls outside the normal range. These coloured tag marks come in a variety of easily recognisable shapes that indicate the importance of a measurement item and the severity of an anomaly (critical, high risk, medium risk, low risk etc.). New audible alarms have been added to provide information on the severity and equipment location of an anomaly.

Committee members include end users, integrators, and suppliers. At present, the committee is comprised of 230 members from many different industries and countries. Members bring lessons learned from many years of designing, integrating, and using various HMI applications.

Establishing a common set of terminology and definitions is vital

As with all standards, establishing a common set of terminology and definitions is vital. The ISA101 committee came up with an easy-to-understand diagram showing what was meant by terms, such as graphic, symbol, and so on (Fig 3).

The standard was approved in June at the ISA Spring Leaders Meeting in Raleigh, NC. "That being the case, we have to go back and address all the comments,” Wilkins says. The committee does not expect to see extensive changes.

Technical standards may take years to develop and technology can change considerably along the way. One such issue is mobility - not on the radar when the committee first formed eight years ago, before the iPhone was even developed.

Will the standard resolve the issues frequently discussed in automation forums, even supposedly simple things like whether red means alarm or stop, and green means go? It seems straightforward, but others will argue that their industries have different uses for those colours. For that reason, the ISA101 standard is unlikely to specify precise colours or exactly how an HMI should look. Instead, it will focus more on things such as on contrast, life cycles and functionality.

Once the standard is published, a series of related technical reports will be prepared by the standards committee. These will cover HMI Philosophy, Style Guidance, Design Guidance, Usability and Performance, Purchase Specification, and Mobile HMIs.

Key Points

  • IAS101 is aimed at those responsible for designing, implementing, using, or managing HMI applications
  • The standard defines the terminology and models to develop an HMI and the work processes recommended to maintain it throughout its life cycle
  • It should improve the user's abilities to detect, diagnose, and properly respond to abnormal situations

 


 
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