Preparing for the second HMI revolution
10 November 2010
Nothing drives new technology quite like a turndown in the economy. Equipment manufacturers have to work harder to differentiate their products, so there is a rush of new features, developments and overall improvements. Andy Margraf turns his attention towards the human-machine interface, or HMI, which has seen some startling advances in recent years
Most machine and control engineers have loved HMIs or graphic display terminals since they first appeared 15 or so years ago. They now offer the ultimate in operator friendliness, and are far simpler and cheaper to install than those traditional arrays of pushbuttons, gauges and warning lights that used to take up so much room on a control panel.
But like all new things, initially they proved too expensive for many applications; but they offered so many benefits to so many systems integrators, machine builders, commissioners and end-users that sales volumes grew and prices came down.
It was to be expected that the technology should plateau after a few years, with fewer new developments and enhancements in the pipeline. But, unlike some well-used pieces of control hardware, HMIs were never destined to become commodities; they always required customising and programming for the 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 a section of an industrial plant, with the screen being used to show a schematic of the machine or process, and its current condition.
Typically the panel will have some integral intelligence that will enable it to alter machine or process settings automatically, in order to maintain certain parameters – the temperature of an oven or the speed of a conveyor, for example. Alternatively, operators can use an HMI to make manual adjustments to settings. HMIs can also be networked, enabling the transfer of live production data to higher order control levels and enterprise management systems.
The HMI market was pretty well established by 2007, but that is not to say that the technology was mature. It was developing on both hardware and software fronts, in part piggy-backing on developments elsewhere.
As flat screen technology was developed for the massive consumer market, HMI manufacturers bought into every new enhancement; and in a similar manner, 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 big players on the HMI scene is CTC Parker. When, like other suppliers in this market, the company was wondering how you make the powerful and dependable HMI even better, it decided simplicity of use and lower unit cost were the goals to aim for. Some three years ago, Parker’s Interact HMI programming software became very popular in the USA where it was widely used for Level-1 applications – essentially, moving from pushbuttons and flashing lights to a relatively simple graphics terminal. The novelty with Interact was its scalability; 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) status, but it covered a very wide range of possible applications.
However, the scalability came at a price, as moving to higher level applications required the purchase of a number of separate modules. Interact version 7 now 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, meeting the demand for flexibility in modern working environments.
Interact 7 has a Windows development environment which makes it intuitively easy to use. It also provides on-line support to simplify applications development, plus menus to assist with previously time-consuming tasks such as alarm and monitoring set-up. This latest version of Interact also performs real time data sharing with other units on the network, improving control and providing redundancy cover in the event of breakdowns or scheduled maintenance. The software is supplied bundled with Parker’s PA2 series PowerStation HMIs, so does not need to be loaded on site.
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 data storage and a variety of connectivity options. Its embedded processor technology supports fanless operation, compact flash storage, USB, serial and 100baseT Ethernet.
Another innovation from Parker is InteractXpress, which fully exploits 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 an upgrade can be developed in one location and instantly distributed to multiple users around the world. This last feature, while not exactly earth-shattering for the determinedly web-wise, nonetheless expands the HMI’s capabilities from that of a simple local controller to a serious piece of hardware at the heart of a widely distributed management network.
At their introduction, HMIs created a quiet revolution in plant and machine control. Now, with recent developments, it looks as if they may be at the brink of a second revolution, taking control from the shop floor environment and making it available to authorised users located anywhere in the world.
Andy Margraf is with AJM Automation, CTC Parker’s UK distributor
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