CAN Over Ethernet Gateways: A Convenient and Flexible Solution to Access Low Level Control Devices

CAN bus is a recommended fieldbus at CERN. It is widely used in the control systems of the experiments to control and monitor large amounts of equipment (IO devices, front-end electronics, power supplies). CAN nodes are distributed over busses that are interfaced to the computers via PCI or USB CAN interfaces. These interfaces limit the possible evolution of the Detector Control Systems (DCS). For instance, PCI cards are not compatible with all computer hardware and new requirements for virtualization and redundancy require dynamic reallocation of CAN bus interfaces to different computers. Additionally, these interfaces cannot be installed at a different location than the front-end computers. Ethernet based CAN interfaces resolve these issues, providing network access to the field busses. The Ethernet-CAN gateways from Analytica (GmbH) were evaluated to determine if they meet the hardware and software specifications of CERN. This paper presents the evaluation methodology and results as well as highlighting the benefits of using such gateways in experiment production environments. Preliminary experience with the Analytica interfaces in the DCS of the CMS experiment is presented.