Bus conducting

Unfortunately such an uncoordinated approach does not provide the best solution for a building in terms of functionality, installation and running costs or future maintenance requirements.

The need for an integrated approach to control initially led to the proliferation of a whole new layer of installer – the system integrator, whose job it was to make sure that all these disparate systems could talk to each other. Anyone who has been involved in such a task will know the complexities of getting several different software systems to interface and provide meaningful and actionable data.

Also if the needs of the building change, questions such as how easy such control is to adapt, or how scaleable it is – either up or down – need addressing.

If all manufacturers’ products and systems used just one software tool and they were guaranteed to talk with each other in a truly open protocol, the benefits to the end user would be great. For such a vision to be realised a manufacturer-independent body would have to develop software and to certify that all products and systems would come together and work.

Out of such thinking the European Installation Bus Association (EIBA) has been born. Established in 1990 by leading European electrical manufacturers seeking a common communication interface, EIBA now has over 150 members, with thousands of interoperable products.

Currently, a European Installation Bus (EIBus) system is the only one that guarantees open protocol. Its ETS software tool is manufacturer-independent and works across disciplines. It is used for every EIB project and every EIB device.

The software offers a single toolbox for designers and electrical installers. Most importantly it is upgradeable, so that today’s EIB systems can add tomorrow’s technology, solutions or products.

Such flexibility is extremely important. Whether in a commercial setting or in the house, the needs of the occupants change and the control system must adapt without messy recabling or refurbishment. Using an open bus system, existing devices are easily changed or taken away and new ones added, all with minimal or no recabling. All you have to do is some simple reprogramming.

The basic technology is simple to understand. This user friendliness means that unlike more complex solutions, occupiers can maximise functionality as well as potential energy and cost savings from a building.

How does an EIBus control system work?

An EIBus is an event-controlled system. Its backbone is the bus line, which is a twisted pair instrumentation and control cable that runs through the entire building. Sensors and actuators – or receivers – link to the bus line via a bus-coupling unit.

Once connected and programmed, all the devices can exchange information. Such data is transmitted serially and according to fixed rules, or bus protocol. This involves packing the information from a sensor into a telegram and transporting it via the bus to one or more actuators.

For example, a light switch and a light sensor might switch or dim certain lights. This same light sensor might also communicate with the blinds on windows and send a message to draw or open them, or even alter the angle of the louvres as daylight levels change.

For this to work, all sensors and actuators have a physical address. Commissioning and programming decide which sensors communicate with which actuators. This allows either single function, or for scene setting, group communication – much like a circular received through the post.

On any one bus system more than 12 000 bus devices can communicate with each other. For clarity each device is assigned a structured address. A simple analogy is the postal system.

The hierarchy is as follows:

• 64 bus devices form a line;

• 12 lines combine to form a functional zone;

• 15 zones combine to form an overall system.

Any sensor, whatever its address, can communicate with any actuator. If in the future this sensor needs to communicate with more or different actuators, it is simply reprogrammed via the bus to communicate with more or new addresses. Unlike other control systems, there is no need for any recabling.

The system makes commissioning, programming and future reprogramming or expansion simple. It also makes diagnostics simpler for maintenance.

Because of the flexibility that bus systems offer, all building services control systems will be based on such technology. There are already several proprietary systems available. For the truly intelligent building to exist, however, we must go one step further to a system that encompasses several different manufacturers’ products – and gives the customer choice.

Potentially this is a huge market, firstly in the commercial and industrial sectors, and soon in domestic residences too. This provides an extremely lucrative opportunity for trained commissioning engineers. It has already happened on continental Europe and the USA. The UK will be close on their tails. Don’t get left behind climb on the bus and get trained now.