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node addressing and topology
EIB is a fully peer-to-peer network, which accommodates up to 65'536 devices. The logical topology allows 256 devices on one
line
. 15 of these lines may be grouped together with a
main line
to form an
area
. An entire domain is formed by 15 areas together with a
backbone line.
On open media, nearby domains are logically separated with a 16-bit SystemID.
Without the addresses reserved for couplers, (255 x 16) x 15 + 255 = 61'455 end devices may be joined by an EIB network.
Installation restrictions may depend on implementation (medium, transceiver types, power supply capacity) and environmental (electromagnetic noise, …) factors.
Installation and product guidelines should be taken into account.
group addressing for run-time efficiency
EIB supports full multicast ("group") addressing.
Full
means that:
- EIB is not limited to grouping devices or functional blocks: each device may publish several variables
(known as "(Group) Communication Objects") individually, which can be grouped independently from one another into network-wide shared variables.
As a bonus, properties of Interface Objects may be published as shared variables as well.
- As explained in the page one EIB run-time communication, a shared variable can be fully read/write bi-directional. In this way, all devices can also send unsolicited multicast frames.
- EIB makes a 16 bit address space available for these shared variables. Even with the limitation of some implementations to 15 bits,
this signifies that one installation may have up to 32k shared variables (or "group addresses"), each with any number of local instances.
The resulting scope and efficiency makes group address communication the preferred "runtime" mode for autonomous EIB field level communication.
In this maybe slightly unexpected way, EIB goes some distance towards reducing the need for redundant automation hierarchy levels (and bandwidth!) through appropriate addressing and device modelling schemes.
IP integration of multiple EIB subnetworks
The above figures hold for one single Field Level EIB network. As pointed out in the
ANubis section
of this web site, several such "subnetworks" may be joined via a megabit IP (Internet Protocol) intranet. This is achieved by smart couplers with routing and mapping functionality. The result provides an integrated control and service networking environment for powerful building control and Service Provider access, with virtually limitless capacity.
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