What is a CAN-Bus?
CAN-Bus (Controller Area Network Bus), developed by the Robert Bosch company, is essentially a digital communications network for controlling devices installed on vehicles. CAN-Bus systems work in much the same way as computer Ethernet networks operate, in that attached devices send and receive signals via a common backbone. All communications are broadcast onto the common bus, with every device listening for a command that relates to it. What differs from a typical Ethernet network, is that CAN-Bus networks also apply power to any attached devices.
Like an Ethernet network though, a CAN-Bus system greatly reduces the amount of cabling (and hence time, weight, complexity and cost) required to create a network. It also allows 'smart' control logic to be applied to the operation of any attached devices, and therefore improves functionality and safety.
A CAN-Bus network is a twisted pair 'bus, that relays digital control signals to and from devices attached to it. This obviates the need to have every switch or control hard-wired to a corresponding device via a power circuit, thereby requiring a more complex wiring harness and one prone to more faults that are less easily traced.
Most vehicles today are fitted with 2 or more CAN-Bus backbones, to which all devices, such as ABS, EMS (Engine Management Systems) and sensors, are attached. Each CAN-Bus typically has a specific function, and is seperated to improve redundancy and safety, as these examples show:
|
BUS Designation |
Systems Controlled |
|
1 - High Speed CAN-Bus #1 |
Engine Management System, Transmission |
|
2 - High Speed CAN-Bus #2 |
SRS (Safety Resttrain System), ABS (Brakes), TCS etc |
|
3 - Low Speed CAN-Bus |
Door lights, Climate Control, Electric Windows etc |
On many modern trucks and buses there is an additional CAN-Bus available to the Vehicle Body Builder. This is known as the BWS or Body Workers System interface. The BWS allows Motor Vehicle Body Builders to easily interface into relevant systems and provide data equivalent to that traditionally received via standard wiring methods, i.e. piggy-backing onto existing sensors.
For example, if you want information such as the engine temperature, oil pressure or whether the handbrake is engaged, you simply connect to the CAN-Bus and read the encoded signal. However, vehicle manufacturers do not readily supply their CAN-Bus codes to after-market fit-out companies or even motor body builders such as emergency services or field service vehicle fit-out companies.
This is done for a number of reasons, but is mostly to ensure vehicle safety, by preventing after-market devices being attached that could cause operational issues with the original systems, or even stop them from working properly.
While vehicle manufacturers might provide the ability to access information from the original CAN-Bus system so that values such as engine temperature or gear selected can be fed to other systems, they do not allow any devices attached to it to be controlled by after-market systems, nor can after-market devices be controlled via this original CAN-Bus.
Therefore, any after-market devices such as emergency sirens, ladder boom position sensors, hydraulic pumps or winches need to be controlled by a separate system, that uses its own wiring loom (generally installed by a motor body builder) and its own control interfaces. This new system will also need to have its own 'control logic' that addresses things such as operator safety and operational performance requirements.
The Impart iCAN System is, simply, an after-market CAN-Bus solution, that delivers all these connectivity, control and safety features to motor body builders and fit-out specialists that delivers all the benefits of the original vehicle CAN-Bus system.
Note that a CAN-Bus is not restricted to vehicle use, but can be applied to factory or portable device automation, as well as be used for devices fitted to aircraft (eg safety winches) or boats (eg winches, lighting and signalling systems), subject to the approval of any relevant certifying or safety authority.
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