CANopen is one of the most advanced system integration frameworks in the market.
Current CANopen design files do not support EECs (emergency error codes) with their human readable descriptions. This article shows how CANopen EECs (emergency error codes) can be described in EDS (electronic data sheet) and DCF (device configuration file) files and how EEC abstractions can be generated automatically for IEC 61131-3 programmable devices from a CANopen project. CANopen design files contain device version information that enables to manage version-specific EECs. Centralized management enables definition of each code once in the producer’s EDS file and unlimited reuse of the codes.
One of the most significant remaining source of inconsistencies in system designs is, how to apply the SI-Units and scaling used by the sensors, actuators and I/O devices to the application programs. Main challenge during the design is that both SI-Unit and scaling may need to be adjusted during the development and it shall be guaranteed that same values will be used by both producer and consumer devices. Though there is not dedicated meta information for SI-Unit and scaling of object dictionary objects, such information can be synthesized from various parameter object values. The approach cannot cover all signals and parameters, but provides an excellent workaround while better support is included into corresponding CANopen standards.
Eliel Saarinen, a Finnish architect, said: “Always design a thing by considering it in its next larger context – a chair in a room, a room in a house, a house in an environment, an environment in a city plan.” That also applies to system design. The main focus of this article is on the re-use of design information within one single CANopen project or between CANopen projects. It is also considered how design information of other disciplines may be systematically used in CANopen projects and vice versa. This approach also emphasizes the possibilities of linked reference data, programmable system data management, and validation. This is in line with the mainstream SW development principles. Systematic re-use means not only the reduction of design efforts but also the reduction of failure costs.
Data transfer over CANopen networks is extremely reliable, but CANopen also offers further safeguards in order to decrease the effect of residual errors further. This article explains the application level safeguards in detail and reviews fundamental CANopen services, which decrease the effect of protocol level residual error probability without introducing any additional life cycle costs. Reviews make sense, because most of the presented concepts have already been not only standardized, but implemented in most of the devices on the market and are just waiting to be used.
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