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17.0 Connecting to a BACnet system
BACnet stands for Building Automation and Control Networks (http://www.bacnet.org). It is a
communication protocol for monitoring and controlling different building regulation systems,
which include heating, ventilation, lighting control, access control, and fire detection systems.
The BACnet protocol uses a common communication format to let these different systems
communicate with each other. A tutorial is available at http://www.bacnet.org/Tutorial/.
BACnet uses a peer-to-peer architecture where any device can send service requests to any
other device. Protocol services include Who-Is, I-Am, Who-Has and I-Have. Any BACnet
object can perform these service requests. BACnet services can provide event notifications
such as troubles or input activations.
The MMX system can interface with other systems that communicate through BACnet. MMX
does not query other BACnet systems. Instead, other BACnet systems can request current
values from the MMX system. MMX only replies to requests or sends out notifications of new
events.
17.1 BACnet Objects
A BACnet object is “a collection of information related to a particular function that can be
uniquely identified and accessed over a network in a standardized way”. Each object has an
object ID and a set of properties.
A confusion of terminology can arise when describing MMX under the BACnet model. In the
fire alarm industry, the term device refers to things such as detectors, strobes, and alarms.
With BACnet, the entire MMX system is a device with many objects. Object refers to all the
fire devices, system statuses and switches connected to the MMX system.
Figure 77 BACnet Objects
BACnet classifies objects into different types. For example, fire devices are divided into
categories such as binary inputs, binary outputs, analog inputs and analog outputs. Every
object has an object identifier, an object name, and other properties. Some properties are
required and some are optional.
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