A CANopen I/O module: simple and efficient system integration

CANopen is a field level communication protocol for industrial automation distributed applications. CANopen offers a powerful set of higher level application layer services which implement an object-oriented distributed environment for simplified system integration. Often, sensors and actuators have to be placed at geographically remote locations, at considerable distances from the processor(s) running a control application. When this is the case, a possible solution is to use an autonomous I/O module, located close to the sensors and actuators, that provides the application with an interface to these devices. The application must be distributed between the remote I/O module and the local processor(s) using a communication network to allow the different parts to cooperate. This work is centred on the development of an I/O module based on the SAB-C167CR-LM chip from SIEMENS. The I/O module makes sensors and actuators accessible via the CAN bus, using the CANopen protocol. The objective is to show that CANopen can be implemented over new hardware platforms, in minimum time, with satisfactory results. It is shown that CANopen provides a systems-integrator-friendly object-oriented environment and that for this reason, the CANopen Communication Profile greatly simplifies the implementation of distributed applications in CAN based systems. Furthermore, CANopen also provides flexible real-time data transfer mechanisms that are able to meet time-critical constraints and, therefore, make CANopen a good solution for distributed control environments.