Field device with CANopen FD communication interface
The CiA 1301 specification is more precise regarding network and device modeling. The network system model introduces the CiA device profile and the CiA application profile approach. The device profile specifies a single CANopen FD communication interface. The application profile specifies all CANopen FD communication interfaces in a network. These interfaces are virtual meaning that the one or multiple virtual devices can be implemented in a single CANopen FD device.
Because CANopen FD integrates a network layer allowing to address CANopen FD devices in other network segments, each CANopen FD devices needs to be addressed by a network-ID plus a node-ID.
The CANopen FD device model as shown includes a CAN entity, which comprises the CAN transceiver and the CAN protocol controller. The CAN protocol controller is in most cases on-chip of the micro-controller – sometimes named host controller. The CANopen FD protocol stack implements the CANopen FD protocols and the CANopen FD object dictionary. And there is the profile and application program of the CANopen FD device, which may comply with one of the CANopen profiles specified by CiA. Of course, the CANopen FD device may implement just manufacturer-specific profiles.
The CANopen FD device’s communication and application parameters accessible by means of the object dictionary are represented electronically in the Electronic Data Sheet (EDS). The EDS provides the parameter and sub-parameter attributes. This includes index and sub-index, name, object code, data type, category (or entry category), access, PDO mapping, value range, and default value. EDS are used to teach device and system configuration tools the provided functionality. Such tools can also be implemented in the host controller with NMT master capability.