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The second HMI revolution

The second HMI revolution
Nothing drives new technology quite like a turndown in the economy. Equipment manufacturers have to work harder to differentiate themselves in the market, so there is a rush of new features, developments and overall improvements. Andy Markgraf of AJM Automation looks at how HMIs have taken a quantum leap forward.

Machine and control engineers have loved HMIs or graphic display terminals since they first appeared 15 or so years ago. They offer the ultimate in operator friendliness, yet are simpler to install than the traditional arrays of pushbuttons, gauges and warning lights. Initially they were too expensive for many applications, but they offered so many benefits that the sales volume grew rapidly and prices were able to come down.

It was to be expected that the technology should plateau after a few years, with fewer new developments and enhancements becoming available. But HMIs were never destined to become commodities; they always required customising and programming to any given application - and that is their great attraction. An HMI is a flat screen graphics display which can be programmed to monitor and control a machine or part of an industrial plant, with the screen being used to show a schematic of the machine and its current condition. 

Typically the panel will have some on-board intelligence so can be used to alter the machine settings, say speeding up an infeed conveyor, or automatically adjusting ovens to maintain a set temperature. Most modern factories have numbers of HMIs on each of their machines. The shopfloor operators can use them to tweak settings, and they are also networked so feed live data up into the control and enterprise managements systems used by managers and directors. So HMIs had an established market by say 2007, but that is not to say that the technology was mature. It was developing in both hardware and software, in part piggy backing on developments elsewhere.

Increasing functionality
As flat screen technology was developed for the massive consumer market HMI makers bought into every new enhancement; and similarly software that would increase the functionality of HMIs was emerging from many sources. The latest HMIs will have a palette of a quarter of a million colours, web connectivity, video and sound capabilities, on-board data processing, massive data capture capacity and a host of other features.

One of the world leaders in HMIs is Parker CTC, part of the global Parker Hannifin Corporation. It was wondering how you make a powerful and dependable HMI even better, and came to the conclusion that they have to become simpler to use and cheaper to buy. Three years ago it was in the position that its Interact HMI software had become the de facto industry standard (at least in America) for Level-1 applications in which users move up from pushbuttons and flashing lights to a relatively simple graphics terminal. Cleverly Interact was scalable, so the same technology could be used on moderately complicated and very complicated applications. It didn't quite reach full SCADA (supervisory control and data acquisition), but it covered an incredibly wide range of possible applications.

However to do this required the purchase of a number of separate modules; so Parker developed version 7 Interact that brings all the modules together into one unit. This means HMIs can be bought in volume and deployed freely to tasks both simple and complex. Further units can be redeployed as required, a common requirement in today's flexible working environments. The cost saving this brings over time are considerable.

Interact 7 has a Windows development environment which is intuitively easy to use. It also includes on-board menus and on-line support to make applications developments as simple as possible. Some of the menus assist with setting up alarms and monitoring, a task that was previously demanding and time consuming. It can perform real time data sharing with other units on the network, improving control and providing redundancy cover for breakdowns and maintenance shutdowns. The software is bundled onto Parker's PA2 series PowerStation HMIs, so does not need to be loaded on site.

The PowerStation is a complete hardware platform, available in a number of sizes and variants. It has a 6in, 8in, 10 or 15in touch screen (also available with no display as a headless unit) with storage and connectivity capabilities to enable it to be networked, to distribute control and data management across the host plant or machine and to feed into higher level control environments. Its embedded processor technology supports fanless operation, compact FLASH storage, USB, serial and 100baseT Ethernet.

Another innovation from Parker is InteractXpress, which fully leverages the wide availability of web browsing software. This enables the HMI to act as a web browser, allowing applications to be developed, edited and published across the Internet, so for example an upgrade can be developed in one location and instantly distributed to multiple users around the world. This last feature, perhaps seemingly mundane in today's web-wise world, expands HMIs' capabilities from a simple local controller to being an integral part of sophisticated widely distributed management networks. 

At their introduction HMIs created a quiet revolution in plant and machine control. Now it looks as if they are on the cusp of a second revolution, taking control from the shopfloor and making it available literally anywhere.
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