Excerpt from A Comprehensible Guide to Controller Area Network © Copyright by Wilfred Voss – esd electronics, Inc. The solution out of this dilemma is the use of distributed control as shown in an example in picture 1.3.1. Each component, digital and analog I/O, and each motion axis is equipped with its own controller. The network connection between all components and the main controller is accomplished with CAN, in this case actually CANopen. CANopen is a higher layer protocol, i.e. additional software on top of the CAN physical and data link layer (Refer to chapter Higher Layer Protocols ). This design provides the ease of adding almost unlimited components (CANopen is limited to 128 nodes, which is sufficient for the vast majority of automation applications.) without performance loss. The number of wires between the components is reduced to two, which not only reduces the cost of the wiring itself, but also reduces time consuming maintenance and service during start up of the machine or in case of malfunctions. The servicing of each component in the network will be improved due to the fact that the engineer only needs to plug the service unit (e.g. a notebook computer) somewhere into the network in order to communicate with either unit. This can be done with only one service software package, since all nodes in the network speak the same language. There is no need for dedicated service programs anymore. The cost saving resulting from the reduced wiring should not be underestimated. A manufacturer in the Boston area produces machinery requiring in average 3 to 5 motion control axes per machine and several hundred I/O points. They overhauled the machine design by using CANopen technologies instead of regular wiring. The cost savings per machine were in the neighborhood of $1,500 per machine. In good economic times they sell 500 machines per year. You do the math… About 90% of all CANopen applications involve at least partly motion control, may it be CAT industrial scanners in the medical industry, sample probing instruments in the chemical industry, wafer handlers in the semiconductor industry, and many more.

1.4 CAN-in-Automation (CiA)

CAN in Automation (CiA), the gate keeper of the CAN standard, is the international users’ and manufacturers’ organization that develops and supports CAN Standards and CAN-based higher-layer protocols. All activities are based on CiA members’ interest, participation and initiative. CiA representatives actively support international standardization of CAN protocols and represent the members’ interest in national and international standardization committees, such as ISO and IEC. CiA members initiate and develop specifications that are then published as CiA standards. These specifications cover physical layer definitions as well as application layer and device profile descriptions. For more detailed information refer to their web site at http://www.can-cia.org .

1.5 International Standard ISO 11898

ISO (the International Organization for Standardization) is a worldwide federation. As its name implies, ISO provides international standards, which are prepared and drafted by technical committees. Each member of the ISO, interested in the subject for whom a technical committee has

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