CANBus (Controller Area Network) is a vehicle bus standard designed to allow smart devices to communicate with each other through a robust, low-cost message-based protocol. But what does that actually mean?
CANBus In a nutshell
CANBus (Controller Area Network) is a vehicle bus standard designed to allow smart devices to communicate with each other through a robust, low-cost message-based protocol. CAN was developed by Robert Bosch in 1986 and was originally designed for multiplex electrical wiring within cars to save on copper but is now used in many other applications such as the elevator industry.
How does CANBus work? Does it differ from traditional networks?
Unlike a traditional network such as USB or Ethernet, CAN does not send large blocks of data point-to-point from node A to node B under the supervision of a central bus master. In a CAN network, many short messages like temperature or RPM are broadcast to the entire network, which means that there is data consistency in every node or ECU of the system.
What are the key benefits of the CANBus?
- Low cost: Devices/nodes communicate via a single CAN interface not through direct analogue signal lines, therefore, reducing wiring errors and cost.
- Centralised: The CAN bus system allows for central error diagnosis and configuration across all devices/nodes.
- Robust: The system has a robust physical layer, designed for high noise and other challenging environments. It provides robust signal transmission whilst providing the user with a flexible network architecture offering a range of data rates.
- Efficient: CAN messages are prioritised via IDs so that the highest priority IDs are non-interrupted
- Flexible: Each device/node contains a chip for receiving all transmitted messages, in order to decide relevance and act accordingly – this allows easy modification and inclusion of additional nodes.
CAN is a multi-serial bus standard for connecting nodes. Two or more nodes are required on the CAN network to communicate.
The complexity of the node can range from a simple I/O device up to an embedded computer with a CAN interface and sophisticated software.
The node may also be a gateway allowing a standard computer to communicate over a USB or Ethernet port to the devices on a CAN network.
Limitations of CANBus
CAN provides the basis for communication but does not provide much more. The CAN standard does not specify how to handle messages larger than 8 bytes or how to decode raw data. A set of standardised protocols exist to further define how data is communicated between nodes on a given network. CANOpen is an example of a common standard which is widely used in industrial automation and elevator applications.
The Future of CANBus
With the rise of cloud computing and Internet of Things (IoT), the adoption of CANBus will increase in all relevant industries including the elevator industry where the data from sensors located in the elevator shaft and cabin will provide data allowing for predictive and preventative maintenance.
CANBus usage in lifts
MEMCO by AVIRE offers a CANBus splitter for digital emergency communications in the lift. It supports the Digital Communication Platform (DCP) connecting with up to 4 CANBus lines, which simplifies wiring for multiple shaft or even single shaft installations, acting as an intermediate between one DCP and multiple Digital Audio Units (DAU).