AlgoRex® CS1140 C-Bus Technical description Building Technologies Fire Safety & Security Products
Data and design subject to change without notice. / Supply subject to availability. © Siemens Switzerland Ltd 1997-2009 We reserve all rights in this document and in the subject thereof.
1 1.1 1.2 1.2.1 1.2.2 1.2.3 1.2.4 1.3 Basic functions .......................................................................................5 Definition ...................................................................................................5 Loop wired (Class A).................................................................................5 Operating condition ...................................................................................5 Behaviour upon short circuit or open line ......
Building Technologies Fire Safety & Security Products 001594_b_en_-09.
Basic functions 1 Basic functions 1.1 Definition Loop wired (Class A) The C-Bus is loop-wired. This provides a redundant line. If a line fault arises (short circuit or open line in a cable) the faulty line can be isolated and communication made via the redundant connection. Stub wired (Class B) The C-Bus is stub-wired. There is no more communication possible if a line fault arises. 1.2 Loop wired (Class A) 1.2.1 Operating condition 1.2.
Basic functions 1.2.4 Behaviour with several line faults in the network If line faults occur in several sections, full communication is no longer possible. The network is then divided into various sub-networks. Once repairs to the line have been carried out, the sub-networks can be reconnected by activating reconfiguration at a CT11. Stations in the isolated sub-network are informed about reconfiguration via the C-Bus emergency line.
Network configuration 2 Network configuration 2.1 Connection of hardware Both C-Bus inputs can each be connected to the input or output via a relay, or terminated with a resistor. In this way it is possible to configure a bus with terminated ends from a loop-wired network. In an intact system only one station may activate a relay and so open a connection.
Network configuration If both relays are inactive, the end-of-line resistors are isolated and the bus is connected (input and output are connected direct). A1 Connection 2 Connection 1 A2 B1 B2 Relay 1 Relay 2 Transmitter / receiver signals The end-of-line resistor must correspond with cable impedance (see appendix: Impedance modification).
Network configuration 2.3 Short circuit or open line on a C-Bus line Stations 1 and 2 disconnect the faulty line from the local C-Bus. Station 1 2.4 Station 2 Station 3 One station is switched off Station 1 is switched off and behaves like a ”piece of wire”. Following reconfiguration, another station takes over the line termination function (station 2 in the example).
Network configuration 2.5 Defective hardware in a C-Bus station A relay test is carried out every time the system is started. If a faulty relay is detected it is automatically isolated. Example 1 Station 1 contains a faulty relay (no contact). The station with the faulty relay can not be the disconnector station. Another station (station 2 in the example) opens the C-Bus loop and closes both ends.
Basic features 3 Basic features Communication between all stations of a local C bus network is also guaranteed if short-circuit or open line occurs on a cable. Each C bus station can opt to connect their signal transformer to a line A and/or line B via relay contacts, the open ends are terminated with resistors. If the C bus is wired as a loop, this results in a redundant connection which can be used in the event of a cable defect.
Appendix: 4 Modifying the impedance of the various C-Bus cables Appendix: Modifying the impedance of the various C-Bus cables This modification is only necessary if the length of the whole C-Bus exceeds approx. 100 meter. C-Bus standard cables have a characteristic impedance of 110 Ω. The driver and end-of-line resistors are soldered to solder lugs and can be adapted accordingly with other characteristic impedances (see diagram below). 1. Explanation A cable must be terminated with resistors.
Appendix: Modifying the impedance of the various C-Bus cables 2. Procedure Request characteristic impedance of the cable from manufacturer (45 Ω ... 200 Ω) Select the value of the Ri the same as the value of the cable characteristic impedance and insert the four end-of-line resistors on the p.c.b. Insert two driver resistors Rd = Ri x 3.65 on the p.c.b.
Siemens Switzerland Ltd Industry Sector Building Technologies Division International Headquarters Gubelstrasse 22 6301 Zug, Switzerland Tel. +41 41 - 724 24 24 © Siemens Switzerland Ltd 1997-2009 Data and design subject to change without notice. www.siemens.com/buildingtechnologies Document no 001594_b_en_-- Edition 09.
