OpenSAFETY
Encyclopedia
openSAFETY is a communications protocol
used to transmit information that is crucial for the safe operation of machinery in manufacturing lines, process plants, or similar industrial environments. Such information may be e.g. an alert signal triggered when someone or something has breached a light curtain on a factory floor. While traditional safety solutions rely on dedicated communication lines connecting machinery and control systems via special relays
, openSAFETY does not need any extra cables reserved for safety-related information. It is a bus-based protocol that allows for passing on safety data over existing Industrial Ethernet
connections between end devices and higher-level automation systems – connections principally established and used for regular monitoring and control purposes. Unlike other bus-based safety protocols that are suitable for use only with a single or a few specific Industrial Ethernet implementations and are incompatible with other systems, openSAFETY works with a wide range of different Industrial Ethernet variants.
and meets the requirements of SIL
3 applications. The protocol has been approved by national IEC committees representing over two dozen countries around the world, and has been released for international standardization in IEC 61784-3 FSCP 13.
openSAFETY supports functional features to enable fast data transfer such as direct communication between nodes on a network (cross-traffic) as well as a range of measures needed to ensure data integrity and accuracy, e.g. time stamps, unique data packet identifiers, and others. One particularly notable characteristic is openSAFETY's encapsulation of safety data within an Ethernet frame: two subframes, each being an identical duplicate of the other, are combined to form the full safety frame. Each of the subframes is secured by its own checksum
, which in effect provides multiple safeguards and levels of redundancy to ensure any distortions of safety data or other types of faults cannot go unnoticed.
, the safety protocol is no longer bound to POWERLINK. Instead, it can be used with various major Industrial Ethernet implementations, namely PROFINET, SERCOS III
, EtherNet/IP
, Modbus-TCP
, and POWERLINK. This broad compatibility with about 90% of the installed base of Industrial Ethernet installations in 2010 is achieved because openSAFETY operates only on the topmost (application) layer of the network, where safety data can be trafficked irrespective of specific network characteristics that may differ from one underlying bus system to another. This approach is commonly known as black channel
operation in communication protocol engineering.
openSAFETY is also the only protocol that has been released as open-source software
, whereas other bus-based safety solutions, e.g. PROFIsafe
, Safety over EtherCAT, or CIP Safety, remain proprietary technology. openSAFETY has been made available under a BSD license.
Following the major openSAFETY presentation in Hanover, proponents of the new solution gave lectures at other industry events as well, e.g. at TÜV Rheinland
’s 9th International Symposium in Cologne, Germany, on 4-5 May, 2010. Speaking at this conference on Functional Safety in Industrial Applications, Stefan Schönegger of Austria’s Bernecker + Rainer Industrie-Elektronik Ges.m.b.H. (B&R
), a co-creator and major advocate of openSAFETY, provided an introduction to key characteristics of the new protocol. Reports on later gatherings indicate that the focus of presentations and discussions about the protocol soon shifted to specific implementation and applicability issues.
Communications protocol
A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...
used to transmit information that is crucial for the safe operation of machinery in manufacturing lines, process plants, or similar industrial environments. Such information may be e.g. an alert signal triggered when someone or something has breached a light curtain on a factory floor. While traditional safety solutions rely on dedicated communication lines connecting machinery and control systems via special relays
Relay
A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal , or where several circuits must be controlled...
, openSAFETY does not need any extra cables reserved for safety-related information. It is a bus-based protocol that allows for passing on safety data over existing Industrial Ethernet
Industrial Ethernet
Industrial Ethernet refers to the use of the Ethernet family of computer network technologies in an industrial environment, for automation and process control. A number of techniques are used to adapt Ethernet for the needs of industrial processes, which require real time behavior...
connections between end devices and higher-level automation systems – connections principally established and used for regular monitoring and control purposes. Unlike other bus-based safety protocols that are suitable for use only with a single or a few specific Industrial Ethernet implementations and are incompatible with other systems, openSAFETY works with a wide range of different Industrial Ethernet variants.
Certifications, Approvals and Key Functionality
openSAFETY is certified according to IEC 61508IEC 61508
IEC 61508 is an international standard of rules applied in industry. It is titled "Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems"....
and meets the requirements of SIL
Safety Integrity Level
Safety Integrity Level is defined as a relative level of risk-reduction provided by a safety function, or to specify a target level of risk reduction. In simple terms, SIL is a measurement of performance required for a Safety Instrumented Function ....
3 applications. The protocol has been approved by national IEC committees representing over two dozen countries around the world, and has been released for international standardization in IEC 61784-3 FSCP 13.
openSAFETY supports functional features to enable fast data transfer such as direct communication between nodes on a network (cross-traffic) as well as a range of measures needed to ensure data integrity and accuracy, e.g. time stamps, unique data packet identifiers, and others. One particularly notable characteristic is openSAFETY's encapsulation of safety data within an Ethernet frame: two subframes, each being an identical duplicate of the other, are combined to form the full safety frame. Each of the subframes is secured by its own checksum
Cyclic redundancy check
A cyclic redundancy check is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to raw data...
, which in effect provides multiple safeguards and levels of redundancy to ensure any distortions of safety data or other types of faults cannot go unnoticed.
Compatibility and Open-Source License
In contrast to all other bus-based safety solutions on the market, which were created to complement a specific Industrial Ethernet protocol or family of bus systems, openSAFETY was designed for general interoperability. Though openSAFETY was conceived by the Ethernet POWERLINK Standardization Group (EPSG) and originally developed as a safety companion to that organization’s own Industrial Ethernet variant, POWERLINKEthernet Powerlink
Ethernet Powerlink is a deterministic real-time protocol for standard Ethernet. It is an open protocol managed by the Ethernet POWERLINK Standardization Group...
, the safety protocol is no longer bound to POWERLINK. Instead, it can be used with various major Industrial Ethernet implementations, namely PROFINET, SERCOS III
SERCOS III
sercos III is the third generation of the sercos interface, a globally standardized open digital interface for the communication between industrial controls, motion devices, and input/output devices . sercos III merges the hard real-time aspects of the sercos interface with Ethernet. It is based...
, EtherNet/IP
EtherNet/IP
EtherNet/IP is a communications protocol developed by Rockwell Automation, managed by the Open DeviceNet Vendors Association and designed for use in process control and other industrial automation applications....
, Modbus-TCP
Modbus
Modbus is a serial communications protocol published by Modicon in 1979 for use with its programmable logic controllers . Simple and robust, it has since become one of the de facto standard communications protocols in the industry, and it is now amongst the most commonly available means of...
, and POWERLINK. This broad compatibility with about 90% of the installed base of Industrial Ethernet installations in 2010 is achieved because openSAFETY operates only on the topmost (application) layer of the network, where safety data can be trafficked irrespective of specific network characteristics that may differ from one underlying bus system to another. This approach is commonly known as black channel
Black Channel
Black Channel may mean:* Der schwarze Kanal , a series of political propaganda programmes broadcast weekly between 1960 and 1989 by East German television...
operation in communication protocol engineering.
openSAFETY is also the only protocol that has been released as open-source software
Open-source software
Open-source software is computer software that is available in source code form: the source code and certain other rights normally reserved for copyright holders are provided under a software license that permits users to study, change, improve and at times also to distribute the software.Open...
, whereas other bus-based safety solutions, e.g. PROFIsafe
PROFIsafe
PROFIsafe is the first open functional safety communication technology for distributed automation systems worldwide. Its specification for PROFIBUS DP and PROFIBUS PA was published first back in spring 1999. It incorporates the knowledge of more than 25 renowned safety companies...
, Safety over EtherCAT, or CIP Safety, remain proprietary technology. openSAFETY has been made available under a BSD license.
Proof of Concept Presentation in 2010
A relatively late arrival on the scene, openSAFETY was first released in 2009. It is based on its immediate precursor technology, POWERLINK Safety, which was originally launched in 2007. openSAFETY won broad public attention in April 2010, when a presentation at the Hannover Messe trade show in Germany showcased four different implementations of the safety solution running in SERCOS III, Modbus TCP, EtherNet/IP and POWERLINK environments. The public presentation and open-source release of the protocol was hotly debated, with strong reactions both in favor and against the new solution, which prompted extensive reporting in the trade press.Following the major openSAFETY presentation in Hanover, proponents of the new solution gave lectures at other industry events as well, e.g. at TÜV Rheinland
TÜV Rheinland
TÜV Rheinland is a global provider of technical, safety and certification services. Originally called the Dampfkessel-Überwachungs-Vereine , TÜV Rheinland was founded in 1872 and has its headquarters in Cologne, Germany...
’s 9th International Symposium in Cologne, Germany, on 4-5 May, 2010. Speaking at this conference on Functional Safety in Industrial Applications, Stefan Schönegger of Austria’s Bernecker + Rainer Industrie-Elektronik Ges.m.b.H. (B&R
B&R
B&R is an Austrian company founded as a Ges.m.b.H in 1979 by Erwin Bernecker and Josef Rainer. Bernecker + Rainer Industrie-Elektronik Ges.m.b.H., with development and production headquarters in Eggelsberg , is currently one of the largest private companies in the field of automation and process...
), a co-creator and major advocate of openSAFETY, provided an introduction to key characteristics of the new protocol. Reports on later gatherings indicate that the focus of presentations and discussions about the protocol soon shifted to specific implementation and applicability issues.
External Links
- openSAFETY official website
- openSAFETY software download area (maintained by communication technology provider IXXAT Automation GmbH on their website)