Definition Of Terms - Siemens Synco 700 Series Basic Documentation

KNX bus
Bus topologies
Bus cable
Bus access method
LTE mode
Zone addresses
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Building Technologies
HVAC Products
1.1.1

Definition of terms

The KNX bus used with Synco is referred to as "KNX TP1". A full-scale KNX
network is a three-level structure consisting of one area line, from which 15 main
lines branch off. A further 15 lines can branch off from each main line. A network
consisting of main lines and lines requires area and line couplers. If no area and
line couplers are used, the network is restricted to one line.
Permissible bus topologies are tree, line and star topologies. These topologies can
be mixed as required. However, ring topologies are not allowed. The tree topology
has advantages over other topologies in cases where a large network has to be
created (refer to "Bus topologies" in the KNX bus data sheet, N3127).
The bus cable comprises two twisted conductors, CE+ (red) and CE– (black).
CE +
CE−
Unshielded bus cables are permitted for the KNX bus in conjunction with Synco
devices. Shielded bus cables are recommended, however, if high interference is
anticipated. For further details refer to data sheet N3127.
The KNX bus uses CSMA/CA (CSMA = Carrier Sense Multiple Access / CA =
Collision Avoidance) to access the bus. With this method of access every bus user
has equal data transmission rights. There is no communication master (in contrast
to the master/slave principle). The data is exchanged directly (peer-to-peer)
between bus users.
A collision avoidance strategy is required when several bus users attempt to send
a message on the bus at the same time (multiple access). One bus user is given
transmission priority, so that it can transmit its telegram fully and correctly. The
other bus users stop transmitting and repeat their message after a given delay.
The CSMA/CA method offers quick response times if the transmission capacity
(number of connected bus users and process events) is utilized within the
permitted limits.
LTE mode (LTE = Logical Tag Extended) is characterized by the assignment of
zone addresses (logical tags) to create communications bindings for the exchange
of process values. Devices with the same zone address exchange process values
with each other, one zone address being capable of transmitting the values of
many data points.
The zones are addressed during local commissioning with the RMZ790 or RMZ791
operator units, or in the case of remote operation, with a PC/laptop and the
ACS7... software.
Basic documentation: Communication via the KNX bus
KNX (Konnex) and Synco
CE1P3127en
30.08.2007