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1
Introduction
1.1
Aims
The software module is being used to connect AVIT and AMX control systems to the "European
Installation Bus" EIB ("Instabus"). It provides an easy to use interface for developers to comfortably
access the
bus.
1.2
Role of the EIB installer
It can not be expressed strongly enough: when connecting to an EIB system, solid knowledge of the
EIB and close contact to experienced EIB installers is strongly recommended. A faulty set Reading
flag in an actuator, or a restrictively programmed line coupler can be really hard to find without good
analysis tools.
There is now way the Netlinx module is able to configure an EIB system. The package is used to
connect to a working EIB, and can access only those bus elements whose usage is permitted.
Because of that, it should be planned together with the EIB installers if all desired functions are
allowed
to the bus components.
1.3
EIB from the AMX programmer’s point of view
Analog to AMX systems is the European Installation Bus – as the name implies – a bus system: all
components are in principle connected to the same wire and share the available bandwidth.
The bus itself is a 2-wire cable, used to supply 24VDC to the devices, as well as transferring data
between them.
Unlike AMX, the EIB system is a decentralized structure – there is no special master controlling the
communication, but any device can send data to any other device.
A sophisticated protocol ensures that only one device is sending at any time, and collisions are
avoided as much as possible.
All communication happens in the form of telegrams. A telegram is a data packet, that consists of the
following parts:
•
Source ID – Hardware address of the transmitting device
•
Destination address – Group address of the receiving devices
•
User data
A telegram can be transmitted to several destination devices at the same time, i.e. to switch off all
lamps in a room simultaneously.
So there is a fundamental difference between both source and destination addresses:
A source address is a hardware address, describing the
device
that is transmitting the telegram.
A destination address is a group address, describing the
function
to be influenced.
Thus each device connected to EIB has exactly one hardware address, but may have several group
addresses.
Furthermore, it is possible and common for several devices to respond to the same group address.
The EIB installer assigns both address types – the hardware addresses describing type and number
of utilized devices and assigned during planning and installation. Hardware addresses are of no
concern for the gateway.
The much more important addresses for AMX are the group addresses.
They define the functions an EIB installation can perform. So functions are simply used by
transmitting specified values to group addresses.
