HMIs - the state of the art and the future

As the world of machinery and process automation is evolving, so is the terminology, says Anthony Mayall.

As the world of machinery and process automation is evolving, so is the terminology.

So, whereas the HMI (human-machine interface) used to be used for low-end products, today the term covers everything from simple operator interfaces that provide access to a PLC (programmable controller), right up to sophisticated systems that could be used as a Scada (supervisory, control and data acquisition) terminal.

HMIs are now widely used throughout the process and discrete manufacturing industries for all types of process visualisation, control and more.

Manufacturing is no longer viewed as an isolated activity within an organisation; MES/ERP (manufacturing execution systems/enterprise resource planning) systems link manufacturing to other functions such as financial control, order management and purchasing, so HMIs are now being expected to link into these far broader-based systems.

Pushbuttons, flashing lights, dials and counters used to form the mainstay of HMIs, but today it is more usual to find colour touchscreens, context-sensitive function keys, or ruggedised keyboards.

Moreover, the HMI is not necessarily mounted on the machinery or even on a swinging arm; Simatic Mobile Panels, recently launched by Siemens, include all the functions that you would expect to find on a fixed panel, but can be taken around the machinery or plant and plugged into the most convenient connection box.

Going a step further, wireless communications technologies enable devices such as the Siemens Mobic mobile industrial communicator to be used anywhere within a plant to monitor processes and, so long as the user has the appropriate authorisation, control the processes.

In today's highly competitive global marketplace, production needs to be optimised, so real-time data needs to be available and visible.

This allows up-to-the-minute decisions to be made about current and planned production, and it is also possible to compare parallel production lines, outputs achieved during different shifts on the same line, and the effect of sourcing components from alternate suppliers.

All of these data can be readily accessed and analysed using state-of-the-art HMIs.

Other uses for HMIs include the provision of standard operating procedures and maintenance instructions.

In particular, if diagnostic information can be accessed, downtime can be kept at the absolute minimum through rapid faultfinding and rectification.

Depending on the IT system installed, a maintenance manager could also use a machine's HMI to view the stock of spares held in the company's stores, or order them online from a supplier.

Leaving aside the benefits that modern HMIs can bring end users, there are also significant advantages for systems integrators.

There is no escaping the fact that the real cost of automation components has fallen dramatically over the last twenty years, and there is now a serious challenge from global competitors with labour costs - including those of skilled engineers - that are lower than in Western Europe.

So if it is no longer possible to trim more cost from the components, the only way to stay competitive is to reduce the cost of the value-added engineering.

For series production, modern mass configuration tools can be used to produce large numbers of 'clones' very easily.

Although the first HMI will still need to be engineered to suit the application, the engineering can be reused to configure the subsequent HMIs with virtually no effort.

Furthermore, tools such as VBA (Visual Basic for Applications) enable engineers to build libraries of software components so that standard elements can be assembled together to create a new application, rather than having to start from scratch each time.

Looking ahead to the next five or ten years, there are more changes on the way that will, again, benefit both the end user and the systems integrators.

Client/server architecture is already being used for Scada systems, which allows the use of lower-specification hardware on the factory floor and avoids the need for multiple Scada licences - both of which can lead to substantial cost savings.

Similarly, web-enabled devices are already starting to be used, though the emphasis is on using the browsing technology rather then the broadcasting technology (distribution of information rather than control).

So, for example, each HMI simply has a browser installed that allows process data to be viewed and instructions to be sent back to a centralised PC.

As the with client/server architecture, hardware and software costs can be reduced.

Other things to look forward to in the future include further measures that will help to reduce the engineering costs, and better integration between the HMI and other components within the automation system.

It is also likely that there will be a continuing trend towards the use of standard operating systems instead of the proprietary systems that used to be favoured by manufacturers of HMIs.

Standard operating systems help the vendors by allowing both the developer overhead and the time to market to be reduced.

And standardisation almost always works in the customer's favour.

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