Technical information
TECHNICAL INFORMATION
212
C-Bus Design Guide
Connection to A Personal Computer
Connection of the PC Interface to the Serial Communication Port of a Personal
Computer is made via the 9 pin D type connector or 2 x RJ45 jacks tted on the Unit.
The installer may also provide access to the PC Interface through a wall mounted
connector, such as the Clipsal 2231/1 data connection plate.
Connection can also be via a C-Bus Network Interface. This will require a C-Bus
Network Interface to be connected to an Ethernet Hub or Switch and a PC with an
Ethernet compatible Network Interface Card (NIC).
Placement of C-Bus Equipment
The placement of C-Bus Output, and System Support Units in any installation is made
with consideration to available space, in relation to other service requirements, such as
air-conditioning ducts and accessibility for maintenance purposes. Many choose to
install the C-Bus hardware in a Clipsal Distribution Panel, located adjacent the relevant
Distribution Board. Input Units are placed as required. Take particular heed of any
specic installation instructions shipped with the product. Sensor devices such as the
Light Level and Temperature Sensors, as well as the Passive Infra Red (PIR) Occupancy
Sensor all require special consideration when choosing an installation location. This
avoids false triggering and erroneous sensor readings.
Every eort should be made to avoid placing C-Bus Equipment Network cabling in
proximity to sources of excessive electrical noise or other electromagnetic interference
(for example heavy inductive motor load switching).
The C-Bus Units have been designed to operate, over an ambient temperature range
between 0˚C and 45˚C, the Units should be placed away from heat sources such as
air-conditioning compressor outlets and hot water services, and Units should not be
covered by insulation material if mounted in the roof space. Avoid installing mains
powered C-Bus equipment in areas of high humidity, such as bathrooms and laundries.
Over Voltages and Transients
C-Bus Side
The C-Bus Network connection of every C-Bus Unit incorporates transient protection
circuitry to safeguard against the eects of unintentionally induced transient voltages.
During transient conditions, information may be lost, however the C-Bus system
incorporates a mechanism to recover from such losses. If the C-Bus is run between
buildings, or there is a likely hood of over voltage conditions, then over voltage
protection is recommended on the C-Bus cable. The over voltage equipment used
should have a rated continuous operating voltage of approximately 50VDC such as an
in-line telephone lter or similar.
8 Practical Wiring Considerations
Mains Side
The mains voltage must be limited to the range specied for any Unit which is mains
powered. Each Unit incorporates transient protection circuitry, and additional external
power surge protection devices is recommended to be used to enhance system
immunity to power surges. It is strongly recommended that over voltage equipment is
installed to protect the C-Bus equipment from transients and over voltage conditions.
Clipsal oer the 970 range of over voltage and over current equipment for this application.
Megger Testing
Megger testing of an electrical installation which has C-Bus Units connected will
not cause any damage to the C-Bus Units. Since C-Bus Units contain electronic
components, the installer should interpret megger readings with due regard to the
nature of the circuit connection. Operation on Isolated Supplies Isolated supplies such
as local generator sites may have inadequate output frequency stability to allow C-Bus
dimmer Units to function correctly. The dimming ability of the C-Bus Dimmer Units
can be aected if the mains supply frequency is out of the specied range. The use of
isolated supplies does not aect the operation of any other C-Bus devices.
Operation on Inverter Supplies
All C-Bus Units which are mains powered are designed to operate from sinusoidal
voltage waveforms. Any inverter which produces a square-wave voltage output may
cause damage to or degrade the performance of the C-Bus devices connected to it.
Working Live on the C-Bus Network
One of the many advantages of the C-Bus safe extra low DC operating voltage, is that
connections can be made whilst the Network is still powered up. Should a short circuit
occur while this is happening, the Power Supply’s output current limiting/overload
circuitry will protect it from damage for an indenite period of time.
Short Circuits on the C-Bus Network
Output Units will assume the state dened on the hardware signifying to the user
that a C-Bus wiring fault has occurred. Units on the C-Bus Network will be rendered
inoperable until such time as the short circuit is removed. No damage can result from
such a short circuit.
Open Circuits on the C-Bus Network
An open circuit on the C-Bus Network may result from a poor termination, or in the
unlikely event of a cable breakage. If C-Bus Units are daisy chained on the Network,
an open circuit may eectively remove C-Bus power from the rest of the Network.
Underpowered or missing Units will not appear on the Network, and will not operate
correctly. This is a good reason to distribute power supplies on any C-Bus Network.
An open circuit will not otherwise aect operation of the C-Bus Network. No damage
can result from an open circuit.
(cont’d)