In the Spring 2023 publication of the CIP family of specifications, ODVA announced the addition of an important new technology, Concurrent Connections which enables flexible, zero switchover time, end-to-end redundancy solutions. Since that time Concurrent Connections sparked interest and evolved. The Concurrent Connections topic was presented at the ODVA 2023 Industry Conference and triggered discussions. The topic resonated at CIP System Architecture Special Interest Group meetings, which resulted in two CIP Specification Enhancements clarifying Concurrent Connections behavior. The Concurrent Connections are the backbone of new CIP Safety solutions.
The Concurrent Connections are inherently coupled with device redundancy. The mechanism of redundancy, both in controllers and devices, is rightly left vendor-specific because it does not impact multi-vendor interoperability. However, vendors would like to see ODVA-defined best practices to implement redundancy in both controllers and devices to simplify their adoption of concurrent connections and ensure that end-user system expectations are met. This paper discusses potential best practices to support controller and device vendors, with a specific focus on these areas that they struggle with today:
- How to coordinate originators of a concurrent connection?
- How to meet the requirements for the concurrent connection payload production on the endpoints of the concurrent connection?
- How to handle concurrent connection payload consumed by redundant devices?
Finally, this paper offers a brief plan for the adoption and implementation of Concurrent Connections technology.
Authors
Filip Zembok, Rockwell Automation
Darren Klug, Rockwell Automation
Jakub Korbel, Rockwell Automation
