CANopen application layer
The application layer of SafetyNET p adapts the mechanisms of CANopen to the conditions of SafetyNET p. CANopen is an open, manufacturer independent fieldbus standard specified/standardized by CiA ( CAN in Automation). SafetyNET p therefore has a standardized application layer for industrial applications. This includes the standardization of communication, i.e. the technical and functional features used to network distributed field
automation devices and standardize application objects via device profiles.
The SafetyNET p application layer is largely based on the CANopen standard. The changes that have been made are mainly in the communications area and in the way safe application data is handled. The key element in CANopen is the object directory, which acts as the interface between the application and the communication subsystem. Essentially it is a grouping of objects and functions, which can then be stored and called up as application objects. The integration of safety functions into the application layer means that the object directory, as the interface to the safe application, needs to be redundant in design.
Generally there are two possibilities for communication between devices: Application data can be merged into process data objects/PDOs (mapping) and then published via the communication system. This is achieved via the cyclical data channel in SafetyNET p. The second possibility is the SDO ( service data object), which is used for acyclic data and is applied when setting control system parameters, for example.
A wide range of device profiles have been developed for CANopen. For example, profiles for digital and analogue I/O devices or drives. By using the CANopen application layer it is possible to use these in SafetyNET p.
