Why it makes sense to merge IT and BMS

IT networks and building management systems are normally kept completely separate. BMS manufacturer Caradon Trend Ltd, believe there is a good case for bringing them closer together.

A modern BMS generally comprises a number of distributed, intelligent controllers (of which there can be hundreds or even thousands) plus one or more operator interfaces. On the vast majority of installed systems, the controllers and user interfaces are connected to a private communications network that exists separate from the other building services.  On large systems this is likely to be made up of a number of inter-linked local area networks (LANs).

Apart from in small buildings, at least one of the operator interfaces usually takes the form of a Windows-based software package running on a standard PC. It seems an obvious step, particularly when the potential benefits are considered, to make this supervisory software part of the IT system. Such a move would involve the IT network taking on the role of the BMS’s communications ‘backbone’ - ie, serving as the internetwork that connects together the supervisors and controller LANs.

A system supervisor can be placed wherever there is a data port, which effectively means anywhere in the building. This feature is especially important when office layouts are changed and people moved around, which in modern buildings happens increasingly frequently.

The high data transmission speeds provided by IT are especially significant in those cases where the BMS has an extensive monitoring role - which more and more do - and data traffic to the system supervisor can reach high levels. For instance, a power failure in a big building could result in hundreds of system generated alarms all occurring simultaneously. For Ethernet, which is the basis for most IT networks and which has a speed of 100mb/s, this sort of situation presents no problem at all.

Integration with IT also makes it easier to provide access to the BMS to those people who ordinarily never go anywhere near it - and may even be unaware of its existence - but who could benefit say from a facility which enables them to view system monitored data, such as the temperature level in their workspace, and where appropriate make changes to setpoints. This could be achieved using very simple software applications. Indeed, the IT network could provide a convenient medium for channelling BMS gathered data to a variety of applications - eg, for sending utility meter readings to an accounts package.

The bringing together of  IT and BMS technology has already happened on a number of sites - among them Eurotunnel’s UK terminal. The latter covers 600 acres and has 20 main buildings, all of which are fitted with Trend intelligent controllers. The terminal’s Ethernet network is being used to link up the controller LANs to create a centrally monitored, site-wide building management system.

This integration of IT and BMS has several advantages. For a start, by obviating the need for a separate BMS internetwork, it reduces infrastructure costs - a saving that is likely to be appreciable on large sites with many buildings. There may also be no need to invest in separate communication links in those situations where a number of sites are remotely monitored from a central supervisor, which is typically done via modem over leased telephone lines. It is probable that the necessary links already exist as part of the IT network, possibly in the form of ISDN (soon it may be the Internet).

However, the most compelling argument in favour of integration is not that it cuts costs. Its principal selling point is that it enables the BMS to take advantage of the IT system’s flexibility and high-speed.
Integration is set to become much more commonplace now that BMS manufacturers are developing products which make it easier to achieve. Trend, for instance, has developed a device that allows a much more ‘plug-and-play’ approach when connecting a controller LAN to Ethernet. Called an EINC, it has two Ethernet connectors - one for twisted pair wiring and one for other media like fibre optic and co-axial cable. Trend has also made it simpler to link its ‘945’ system supervisor to Ethernet. Connection no longer requires a serial port server but can be effected directly through a PC network card.

The normal operation of an IT network is in no way affected by its use for BMS traffic. Nor does integration compromise the functionality or essential features of the building management system. This is because the BMS continues to use its own proprietary messaging protocol, the IT network merely acting as a transport medium - albeit a very efficient and flexible one. Also, integration only occurs at the system’s management level - where it is needed - not at the field and control network levels. Keeping matters simple means that the end-user enjoys all the benefits yet loses nothing.