CANopen history

In November 1994, CiA published the very first version of the CANopen specification: CiA 301 is one of the most successful Esprit research projects. The CANopen success story is unique, because it was not promoted by one big supplier but by many medium-sized and small companies as well as machine builders.

1993 Pre-development of CANopen within an Esprit project under the chairmanship of Bosch 1994 Publication of the CANopen predecessor CAL-based communication profile version 1.0 1995 Publication of CiA 301, CANopen application layer and communication profile 2.0 1996 Publication of CiA 301, CANopen application layer and communication profile 3.0 1999 Publication of CiA 301, CANopen application layer and communication profile 4.0 (EN 50325-4) 2007 Publication of CiA 301, CANopen application layer and communication profile 4.2 (for CiA-members only) 2011 Publication of CiA 301, CANopen application layer and communication profile 4.2 (public)

In the beginning, the CANopen specification was named "CAL-based communication profile for industrial systems". It was developed under the umbrella of Esprit (European Strategic Program on Research in Information Technology), a research program of the European Community. The title of the project 7302 was ASPIC, short for “Automation and Control Systems for Production Units using an Installation Bus Concept”. The objective was to develop control architectures and devices to enable flexible and modular combinations of existing manufacturing cell units. The researchers led by Dr. Mohammad Farsi (University of New Castle) and Stefan Reitmeier (Bosch) decided to use the CAN Application Layer (CAL) protocol, developed by CiA. CAL was a pure application layer approach according to the OSI (open systems interconnection) model. However, it was in some respects an academic approach and had various fathers: Its main contributions came from Tom Suters (Philips Medical Systems), as well as Prof. Dr. Konrad Etschberger and Prof. Dr. Wolfhard Lawrenz both working at German universities for applied science. Of course, other CiA members also contributed ideas.

The ASPIC project’s objective was to develop an application layer that was easy to implement, dedicated to embedded machine control. Under the leadership of Bosch, several companies (Moog, ADL Automation, and J.L. Automation) and institutes (Newcastle University and Reutlingen University of Applied Sciences) specified the first version of what is known today as CANopen. The main contributors were Dr. Mohamad Farsi and Prof. Dr. Gerhard Gruhler. The first version already defined PDOs (process data objects) and SDOs (service data objects). The synchronous transmission of PDOs was introduced as well as Network Management (NMT) and Emergency messages.

In the early days of CANopen, CAN remote frames were still in favor, which is why Node Guarding was based on them. Later, Node Guarding was substituted by the Heartbeat mechanism. The first CANopen networks also used remotely requested PDOs. Nowadays, CiA recommends not using remote frames at all.

The CANopen specification published as CiA 301 was one of the most successful Esprit research projects. One of the reasons was that the specification was handed over to CiA for further developments and maintenance. From the beginning, several companies implemented the higher-layer protocol in real applications. Of course, several reviews and updates were necessary before CANopen became a stable specification. Version 3.0 was the first release used in products and systems. This version was valid from 1996 to 1999. Some applications still use this version today.

CANopen can be regarded as the application layer of small and medium-sized suppliers. It is the only independent industrial communication system not promoted by one market-leading company. It can also be regarded as the solution of system designers, because some machine builders have chosen this approach to be independent from suppliers. Among these machine builders are Heidelberger and Siemens Healthcare. In 1995, CiA presented the very first CANopen multi-vendor demonstrator equipped with products from Moog, Selectron, and others at its Hanover fair booth.