Safety over EtherCAT conformance test benefits

In industrial safety applications where life and limb are at stake, or where valuable machines and manufactured goods require protection, safety devices help ensure the necessary safety measures in the field. In the event of a fault, they trigger mechanisms at lightning speed such as forcing an emergency stop of a machine to ensure the safety of the application and, above all, the operator. To confirm this high level of safety, the manufacturers of these devices are subject to official requirements during development, testing and implementation.  Certified safety devices include safety I/O modules, safety programmable logic controllers (PLCs), drive controllers, encoders, and programming software for safety.

The EtherCAT Technology Group (ETG) offers manufacturers of Safety over EtherCAT (abbreviated FSoE for FailSafe over EtherCAT) devices an ecosystem with a wide range of support services such as tools, tests, documents and consultation. The central component of these support services is the FSoE Conformance Test, which is mandatory for manufacturers.

Is a conformance test mandatory for safety device manufacturers?

The development of functional safety devices is associated with a rigorous formal effort, which on the one hand results in high quality hardware and software, and on the other hand also ensures verifiability. Finally, before the market launch, a recognized test center must prove the entire implementation meets the requirements of the desired safety integrity level (SIL). In addition to the actual safety-relevant function of the application (such as safe emergency stop or safely limited speed for a drive), proof must also be provided for the reliable and standard-compliant implementation of the Safety over EtherCAT protocol.

One option for this is theFSoE Conformance Test, which is carried out by an officially recognized FSoE test service provider in the EtherCAT Test Center. According to the FSoE Policy, each manufacturer is obliged to perform this test, which in itself already constitutes a subset of the formally required proof overall.

Even if the FSoE Conformance Test only represents a relatively small part of the obligation to prove the safety of a device, it nevertheless provides great added value for the manufacturer – especially in connection with the other test options offered by ETG. The conformance test increases the reliability, freedom from errors and interoperability of secure communication and ultimately customer satisfaction.

What happens in an FSoE Conformance Test?

The prerequisite for the FSoE Conformance Test is the EtherCAT Conformance Test, which checks if the basic EtherCAT implementation works reliably. If this is not the case, and if errors already occur in the underlying communication, the safety function is often triggered in a machine, which makes it a supposedly safe machine, but drastically reduces its availability and throughput.

If the device passes the test for the EtherCAT protocol, the conformance test checks the implementation and integration of the FSoE protocol.

Who conducts FSoE Conformance Tests?

In Germany, the FSoE Conformance Test is carried out by TÜV Süd Rail, which is recognized as one of the world’s leading institutions in industrial device testing and verification. The test is also internationally recognized by other test facilities commissioned by the manufacturer for the overall verification, such as TÜV Nord or TÜV Rheinland. In addition, the FSoE Conformance Test is based on a world of specifications already confirmed by TÜV Süd: The FSoE specification ETG.5100 was certified in 2005 and has been part of the international standard IEC 61784-3 FSCP 12 (Functional Safety Communication Profile) since 2010.

The ETG.7100 test definition in the form of a test table also has been approved by TÜV and covers the tests for FSoE slaves as well as masters, enabling every device manufacturer to implement it in their own test environment. Through the integration of these tests into the EtherCAT Conformance Test Tool (CTT), the tests can also be automated and performed in a repeatable manner. This also is done during the official FSoE Conformance Test and serves device manufacturers during the development and integration of the FSoE stack into their devices and, in preparation for acceptance in the EtherCAT Test Center.

EtherCAT interoperability tests

The EtherCAT Technology Group offers manufacturers additional assistance in the planning, development and testing of FSoE devices. An important document is the Safety over EtherCAT Implementation Guide, which provides relevant information for implementation best practices. It contains all references to specifications and documents as well as the available facilities for training, support, development products and services and testing.

In addition, developers have the opportunity to participate in EtherCAT plug fests, which take place worldwide several times a year and are considered a pragmatic approach to testing the functionality and interoperability of their own devices and stacks with those of other manufacturers. In addition EtherCAT plug fests, where tests specific to both EtherCAT and FSoE protocol can be performed and questions can be answered, there is a special plug fest once a year for only FSoE device manufacturers.

The interoperability of FSoE slaves, masters and configuration tools is tested here. At plug fests manufacturers can validate their own implementations in the prototype stage and prepare for the EtherCAT and FSoE Conformance Test.

As with the EtherCAT base protocol, the EtherCAT Technology Group offers an ecosystem around FSoE implementation, testing and release. The organization’s goal is to support manufacturers of FSoE devices in realizing implementation as quickly and successfully as possible and to go through the acceptance process as smoothly as possible.

FSoE testing process

The FSoE conformance test is carried out by TÜV Süd Rail at the EtherCAT Test Center in Nuremberg, Germany. There, the device manufacturer can have the EtherCAT Conformance Test, which is mandatory as a basis for general EtherCAT implementation, carried out in one day. If this test is passed, the FSoE Conformance Test is usually performed the following day.

Christiane Hammel is public relations at EtherCAT Technology Group, Nuremberg, Germany. Edited by Chris Vavra, associate editor, Control Engineering, CFE Media and Technology, cvavra@cfemedia.com.

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Keywords: Ethernet, EtherCAT

ONLINE

Learn more about FSoE at www.ethercat.org/en/safety.html

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