North Building Technologies

While the increased use of a low level field bus simplifies the connection of components within a building services control system, the high level monitoring and control of these systems remains cumbersome in most buildings.

In a reasonably advanced situation each has its own "top end", and these may be connected back to one PC, making use of the serial ports available. But even then, each will normally be using different software so the user has to load programs to switch from one to the other.

There is also the problem of geographical location. Fire panels, lighting control centres and hvac control systems are often, for logical reasons, located in different parts of the site. Bringing these communications back to a central point can be expensive and technically difficult. In the worst situation, therefore, the building operator may have his or her supervisory terminals scattered all over the building, each limited to the control of just one system.

The obvious solution would be to integrate all of these systems at a high level so they can talk to each other and can be accessed from the same software on the same terminal. This "integration" has been a buzz word in the controls industry for several years. Indeed, most controls manufacturers pay a considerable amount of lip service to promoting the concept. When it comes to actually realising this objective, however, self-interest and inter-company bickering seems to obviate any real progress.

High level networking

Compass provides high level networking and integration functions for the ObSys display and other 3rd party systems. A fundamental design philosophy behind Compass is the use of a communications driver, each written for a particular manufacturer's control system which allows it to pass values to and from the system in the manufacturer's own language, or protocol.

These drivers allow any system, such as hvac, lighting, security, fire, power, etc., to talk to each other using Compass as a wide-area network. This is achieved without altering the control manufacturer's own software so that any combination of systems can be brought together on one PC through the same software.

An established stock of more than 200 communications drivers already exists for a range of systems and communication equipment and the range is being extended as the need arises. There are a number of advantages to this approach. For one thing, Compass can transfer information much faster than most advanced building control systems and low level field buses. This enables Compass to handle substantial amounts of building information without any significant delay. In contrast, earlier systems for linking have tended to slow the whole process down.