Delta DVP-15MC Series, Operation Manual

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DVP-15MC Series Motion Controller Operation Manual
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About CANopen protocol
The CAN (controller area network) fieldbus only defines the physical layer and data link layer. (See
ISO11898 standard.) It does not define the application layer. In the practical design, the physical
layer and the data link layer are realized by the hardware. The CAN fieldbus itself is not complete. It
needs the superior protocol to define the use of 11/29-bit identifier and 8-byte data.
The CANopen protocol is the CAN-based superior protocol. It is one of the protocols defined and
maintained by CiA (CAN-in-Automation). It is developed on the basis of the CAL (CAN application
layer) protocol, using a subset of the CAL communication and service protocols.
The CANopen protocol covers the application layer and the communication profile (CiA DS301). It
also covers a framework for programmable registers (CiA 302), the recommendations for cables
and connectors (CiA 303-1), and SI units and prefix representations (CiA 303-2).
In the OSI model, the relation between the CAN standard and the CANopen protocol is as follows.
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The object dictionary
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CANopen uses an object-based way to define a standard device. Every device is
represented by a set of objects, and can be visited by the network. The model of the
CANopen device is illustrated below. As the figure below shows, the object dictionary is the
interface between the communication program and the superior application program.
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The core concept of CANopen is the device object dictionary (OD). It is an orderly object
set. Every object adopts a 16-bit index for addressing. In order to allow the visit to the single
element in the data structure, it also defines an 8-bit subindex. Every node in the CANopen
network has an object dictionary. The object dictionary includes the parameters which
describe the device and the network behavior. The object dictionary of a node is described
in the electronic data sheet.