The Controller Area Network
(CAN) is a serial communication way, which efficiently
supports distributed real-time control with a very high level of
security. It provides the error process mechanisms and message priority
concepts. These features can improve the network reliability and
transmission efficiency. Furthermore, CAN supplies the multi-master
capabilities, and is especially suited for networking ¡§intelligent¡¨
devices as well as sensors and actuators within a system or sub-system.
To seek an industrial environment with higher performance and stabilization, ICP DAS provides you a new communication way (CAN Bus). We have a team with strong technical background and experiences, and have been developing and studying CAN bus for years. ICP DAS will always secure your industrial safety and stable automation system as our mission.
The
CAN Applications
• Factory automation •
Industrial machine control • Maritime electronic
• Building management system •Aircraft engines
CAN
Multi-master
When the CAN bus is free any node may
transmit a message to another node. Safety CAN provides five mechanisms
for detecting errors. The CAN bus error rate is less than 4.7x10-11 Speed & Distance When the CAN bus speed is 5KB/s,the
farthest distance is 10km.
When the CAN bus distance is 40m,the fastest speed is 1MB/s. Arbitration If two or more nodes start transmitting
messages at the same time, the arbitration mechanism was started.
During arbitration every transmitter compares the level of the
bit transmitted with the level that is monitored on the bus.
If these levels are equal the node may continue to send. When
a level of the bit transmitted is different form the level monitored,
the unit has lost arbitration and must stop sending one more
bit.
DeviceNet based on the CAN bus is one of the world's leading device-level
networks for industrial automation. In fact, more than 40% of
end users surveyed by independent industry analysis report choosing
DeviceNet over other networks. It offers robust, efficient data
handling because it is based on Producer/Consumer technology.
This modern communications model offers key capabilities that
allow the user to effectively determine what information is needed
and when.
The Components in DeviceNet
A device within a DeviceNet network is represented
by an object model. The object model provides a template for organization
and implementing the attributes (data). Services (methods or procedures)
and behaviors of the components within a DeviceNet product. The
following figure depicts the object model of DeviceNet Gateway
(Group 2 Only).
Features
• A cost effective solution to
lowlevel device networking
• Access to intelligence present in lowlevel devices
• Master/Slave and PeertoPeer capabilities
• Trunkline/dropline configurations
• Support for up to 64 nodes
• Selectable data rates of 125k baud, 250k baud, and 500k
baud
• Use of Controller Area Network (CAN) technology for Media
Access Control and Physical Signaling
• Connectionbased model to facilitate application to application
communications
• Provisions for the efficient movement of I/O data
• Fragmentation for moving larger bodies of information
• Duplicate MAC ID detection
CANopen is a kind of network protocol based on CAN bus and has been used
in various applications, such as vehicles, industrial machines,
building automation, medical devices, maritime applications, restaurant
appliances, laboratory equipment & research. It allows for
not only broadcasting but also peer to peer data exchange between
every CANopen node. The network management functions specified
in CANopen simplifies the project design. Besides, users also
can implement and diagnose the CANopen network by standard mechanisms
for network start-up and error management. By the device model,
any CANopen device can effectively access or get the conditions
relating to the I/O values and node states of other devices in
the same network. Generally, a CANopen device can be modeled into
three parts.
Communication
This function unit provides the communication objects and the
appropriate functionality to transport data items via the underlying
network structure. Object Dictionary
The Object Dictionary is a collection of all the data items which
have an influence on the behavior of the application objects,
the communication objects and the state machine used on this device. Application Program
The application comprises the functionality of the device with
respect to the interaction with the process environment
Features
• Configuration for the entire
network.
• Easy access to all device parameters.
• Device synchronization.
• Cyclic and event-driven data transfer.
• Up to 128 nodes can be participated in the same CAN network.
• High transmission speed.
• Open architecture.
• CANopen is maintained by CiA (http://www.can-cia.com/).
