In order to reduce the risk of electrical faults bringing a vehicle to a standstill and at the same time produce benefits from rational fault- tracing and service, Scania has developed a new electrical system – the BNS (Body Node System). This controls most of the main functions in the OmniCity bus, and can be programmed for the full range of customer requirements. It is situated in the roof behind a hatch to the right of the driver.
Regulating functions such as the door-opening mechanism, interior lighting and climate unit, the new electrical system is based on the node system: instead of routing a specific cable from the electrical distribution centre to each relevant unit, all the electrical components are supplied from eight fixed nodes or sockets. The nodes feature microprocessors which regulate activation and deactivation of the various current consumers, and information to all the nodes is transmitted along the same cable.
Scania says there is a dramatic reduction in the amount of wiring needed in the bus resulting in a weight saving of 70kg in terms of wiring alone. Installation is simpler, the potential for errors is reduced and the physical system is the same for all vehicles, since customer-specific variations are created simply by programming the system.
BNS can be programmed for the full range of customer requirements. A basic program is entered during initial assembly, and this can be easily altered to suit operator needs. Neither is there a requirement for large complex wiring diagrams. A simple diagram showing the routing to the various current consumers on each node is sufficient.
Another benefit is that the system allows computerised fault-tracing and on-board diagnosis. There is a socket for Scania Diagnos – software for fast fault-tracing – which offers information about the fault, the likely component that needs replacing and its exact location. No additional electrical wiring diagrams are required as all the relevant information is already stored in the software.
An on-board computer can also be connected to the system. This computer replaces several separate control systems for functions such as ticket handling, destination signs, communication radio and panic switch, automatic bus-stop announcement, automatic gate and barrier opening, automatic switching of traffic lights to green on approach, traffic guidance and passenger counting.
Without leaving the driving seat, the driver can also use the computer to carry out some of the daily pre-driving inspection checks (such as checking the vehicle lights) before starting the shift.