Table of Contents
Advertisement
KNX bus
Bus topologies
Bus cable
Bus access method
LTE-Mode
6 / 88
Siemens
Building Technologies
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.
Allowed bus topologies: Tree, line and star topologies. These topologies can be
mixed as needed. However, ring topologies are not allowed. The tree topology has
advantages over other topologies in cases where a large network has to be created
(see "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 to exchange
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.
KNX bus communications
KNX and Synco
For internal use only
CE1P3127en
2013-04-08
- Quick Links:
- General Overview
- Knx and Synco
- Faults and Errors
Hide quick links:
Advertisement
Table of Contents
