In factory automation (FA) and process control, networks and protocols of the operation technology are more and more merged with those of the information technology (IT). The requirements of operational technology (OT) and IT are different. Modern networks and protocols for communication in FA and process control systems must take care of the coexistence and convergence between the IT and OT worlds. Due to historical developments, the standards for OT were and remain defined by the International Electrical Commission. The IT, on the other hand, is the domain of the International Telecommunication Union and the International Standard Organization (ISO), which takes over most of the standards in the communication field from the IEEE Standard groups 802. This paper provides an overview of the standardization bodies involved and provides examples on how different requirements introduced by OT and IT can coexist. The merging of OT and IT on an Ethernet network with time-sensitive networking is the key technology for real-time applications in the factory floor. The adoption of the industrial protocol OPC UA provides secure connections from the factory floor to automation cloud infrastructures. IO-Link wireless, as new standard for sensors and actuators in OT, provides coexistence mechanisms toward wireless standards in IT applications such as IEEE 802.11. These examples show that there are possibilities to coexist and even to merge the standards and technologies of OT and IT in a successful way.

With Audio and Video Bridging (AVB), the Institute of Electrical and Electronics Engineers (IEEE) AVB task group introduced Real-Time capabilities to Ethernet based on IEEE 802 Standards. As AVB was conceived with a focus on home and professional audio and video transmissions, some mandatory aspects for the application in industrial control networks are not covered. Under the name of Time-Sensitive Networking (TSN), second generation AVB standards are being developed to address the requirements of industrial automation and control networks, and automotive in-vehicle networks. One of the mandatory requirements addressed by TSN is a redundancy feature to achieve fault tolerance. This paper compares two methods for implementing fault-tolerant networks with the stream registration mechanisms that are planned for TSN.

The Audio and Video Bridging (AVB) technology equips Ethernet with Real-Time characteristics, based on standards developed by IEEE 802.1. In 2011, the IEEE 802.1 AVB Task group completed the first generation of AVB Standards, and is currently starting standardization work on AVB Generation 2, aimed at Industrial Automation & Control networks, as well as Automotive networks. One aspect of this standardization effort is to adapt AVB stream reservation mechanisms to operate with industrial-standard fault tolerance technologies. This paper proposes a method to allow AVB to be used flexibly with different use-cases and different stream configuration mechanisms to achieve fault-tolerance. The method has been verified through simulation and has been proposed to the AVB task group for inclusion into the 2ndGeneration AVB standards.

Industrial Ethernet networks are now a common feature on today's factory floors. Vendor-specific technologies, such as Profinet IRT, have demonstrated Ethernet networks with hard real-time (RT) properties. Specified by the IEEE, the Audio and Video Bridging (AVB) technology promises a standardized approach to RT Ethernet. However, AVB has been conceived for other application fields, e.g. home entertainment systems. Several aspects necessary for AVB's potential use in industrial automation solutions are not covered by the standard. One important aspect is the usage of redundant communication paths to increase fault tolerance. In this paper, a method of achieving redundancy with AVB is proposed. It has been verified through simulation and has been proposed to the AVB Task Group for use in future revisions of the standard.

Ethernet ring redundancy is becoming a commodity in Industrial Ethernet environments. There are many ring redundancy protocols in existence, both standardized and proprietary. They all share the common disadvantage, that they can sustain only one fault in the network structure. A second fault results in parts of the network being unavailable. In this paper, we propose a mechanism which enhances well-known ring redundancy protocols with the capability of tolerating more than a single fault. This is achieved by installing secondary network paths and adding health monitoring to the ring clients. Protocol operation has been tested through simulation and prototypical implementation and is intended to be part of a future major software release of Hirschmann switches. A main advantage of this new protocol is the straightforward network design approach that enables to specifically protect vulnerable ring segments, based on availability calculations.

Of the numerous industrial Ethernets specified in IEC 61158 & IEC 61784, few provide physical redundancy and none provides a redundancy method that is independent of the upper layer protocols.

In modern communication systems based on Ethernet technology, the use of physical ring structures and ring redundancy protocols has been common for some time in the past. A challenge remains the configuration of such a redundancy protocol on each device with the networks stretching out over large areas, like in offshore wind power stations, where each windmill houses at least one Ethernet switch. The distance between windmills can be several kilometers and configuration of the redundancy protocol on each device is an elaborate process. In this paper, a mechanism is proposed which automatizes the configuration of ring redundancy protocols and eliminates the need to configure each device separately. The actual protocol implementation is intended to be part of the next major software release of Hirschmann Industrial Ethernet Switches.

Industrial networks used to control production machinery require high availability to keep possible productivity losses to a minimum. The challenges to overcome are how we are to acquire the needed device information - also with a possible network error already in place - and how to process and pass on this information in order for errors to be quickly fixed. We took possible error scenarios and the data available on the devices to determine which errors can be detected and processed and propose a system of abstraction which provides administrative and service personnel with means to quickly and efficiently identify and fix detected errors.