CiA 408 defines the CANopen-based control interface for valves including device state management, control signals, and common device parameters. This article introduces CiA 408, describes a valve controller deployment, and discusses deployment with experiences from real-system projects.
Many of us is thinking every now and then, would it make sense to throw away other network technologies and just use Ethernet or WiFi for everything? It sounds attractive, that single network does everything, only a single tool chain is required and only single technology needs to be learned. At a first glance the answer is ”of course”, but after thinking a while, the answer turn into ”of course not”.
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New core services in the domain of IoT concentrate on early detection of various exceptions in the target process. The earlier detection shall work, the smaller deviations shall be detected. Reliable identification automatically requires significant improvement in measurement accuracy. Most automation engineers have not identified, that the basic instrumentation needs to upgraded before the all new analytics can work as designed. Read more
Residual error analyses for CAN networks have been performed for years. It is well documented, that commonly used equations do not fully apply for analytic computing of the residual error probability of CAN networks. Also too high bit error probability values have commonly been used in the analyses. Furthermore, CANopen networks have been analyzed as CAN networks, without taking into account the additional safeguards provided by various CANopen services. Results have been very pessimistic, which has lead to significant unnecessary cost and complexity in various applications.
Despite of the comprehensive knowledge of the CAN physical layer, there is poor tradition in design of physical layer structures for industrial and machinery CAN networks. Cables with “wrong” impedance (not matching with termination) are commonly used and many engineers intentionally select them, because of constrained understanding of the transmission line behavior.
In many applications, complex safety add-ons have been designed on top of existing control systems, which has lead to significantly increased complexity and costs. The most significant increase of the performance level can be achieved by replacing all analog signal paths with digital communication: as long as an error can be detected and a control system can perform a reliable reaction, the error cannot cause any harm. When typical failures of systems are analyzed, it is obvious that analog signal paths are the weakest point of any control system.
Systematic re-use of information and design processes defined by the selected system integration framework, such as CANopen, should be understood as an integral part of companies’ design, assembly and service operations, instead of “just another communication protocol” in individual control systems. There are many use cases for such kinds of system integration framework in system design, assembly and service activities.
Multiple disciplines for mechatronic system design co-exist, which hinder the utilization of software-oriented modeling principles e.g. UML. Existing modern tools may be integrated into a working tool chain.
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Current CANopen design files do not support EECs (emergency error codes) with their human readable descriptions. This feature has become more problematic because of abstraction to parameters and signals. The system structure has become automated and proven way of working. Manual EEC management is decreasing the development efficiency because it is time-consuming and prone to inconsistent codes. These design projects are iterative and effort is wasted on each cycle of each project by managing EECs manually. Descriptions shall be uniformly defined for both producers and consumers. Read more
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