Alternative Method of Diagnosing CAN Communication

Abstract

The article discusses a suggestion for an alternative method of diagnosing communication in the CAN standard (Controller Area Network). Currently, a CAN communication bus is available not only in vehicles for which the standard was designed, but also in industrial plants. A CAN communication bus connects elements of, e.g. distributed control systems, vehicle onboard systems, remote intelligent I/Os of industrial controllers. The devices connected via the bus communicate in a broadcast mode. IDs (numbers) are assigned to messages and not devices. This enables simultaneous sending of a message to all awaiting recipients. A prerequisite for the correct functioning of the aforementioned systems is their proper operation, and primarily, maintaining the communication system in a state of fitness. Information regarding the sent variables are necessary to test the functioning of a data transmission system. It is the communication diagnostics that provides information necessary to formulate a diagnosis regarding the communication system condition. Based on the collected data sent in the messages, it is also possible to develop relevant remedial actions. In the case of CAN standard transmission, the diagnostic information can be acquired through intercepting and analysing the messages sent to the communication bus by communicating devices. The article suggests replacing often costly CAN bus analyser hardware solutions with a simpler one – an operator-diagnostic station – a computer equipped with an industrial CAN expansion card. By applying the right middleware, and the use of a standard visualization package, it is possible to monitor the data sent in CAN messages. This elaboration presents a concept of diagnosing communication using a standard SCADA visualization package, which is run on a diagnostic-operator station using middleware – a control window embedded directly in the synoptic image and a software gateway. This solution makes receiving (monitoring, visualization) and sending (testing) data frames to a CAN bus feasible.