In 2011, ODVA announced a new machinery initiative in cooperation with two alliance partners – OPC Foundation and Sercos International. The three organisations collaborated on a white paper, published by ODVA in November 2011, describing their shared vision for this initiative. The white paper pointed out that, in an environment characterised by multiple networks and communication technologies, a key integration problem is how to reduce the number of heterogeneous communication and connection interfaces. This brief describes anticipated next steps in this initiative pertaining to the technical approach to solve this key problem.
One aspect of the problem is how to enable standard reporting methods and tools to aid in the asset management of machines and the monitoring of their states. To solve this problem, a technical approach is being pursued for a protocol-neutral data model that standardises the reporting language for basic information about a machine, including its basic awareness attributes and states. Adapted to specific technologies – CIP, Sercos and OPC UA – this data model will provide the means to collect data from individual machines or to aggregate data from multiple machines at various levels of the enterprise, and present this data consistently at all levels: from the machine to the process level, the system level and ultimately to the production and enterprise domains. This will be achieved with the integration of machine data based on logical groupings of data.
Methods developed in CIP, OPC and Sercos to access a common set of data attributes, and deployed in conjunction with machine applications, will result in a unified integration model designed to support access to information on base machine data, condition monitoring, energy and safety, among others. In addition, data models that have been developed for specific machine applications such as packaging, machine tool and semiconductor can instil the machine with a personality. Inclusion of personality machine data, developed by standards groups in these machine segments, is essential to leveraging the application-specific know-how that is core to a machine’s successful operation.
Another aspect of the problem in this environment is the need to connect the machine to multiple network infrastructures. To solve this problem, one technical approach that has been investigated and found to be feasible in specific scenarios is to combine Sercos III and EtherNet/IP compliant devices on an integrated network infrastructure. This approach can allow machine builders and users to reduce the cost and complexity of machine integration while retaining the ability to deploy their preferred product suppliers and devices.
Mix and match
Because the required infrastructure for both the EtherNet/IP and Sercos III networks includes physical and data link layers of Ethernet, it is possible for CIP messages, TCP/IP messages and Sercos telegrams to co-exist on the same wire. This will be achieved by starting with a Sercos III network infrastructure, connecting one or more EtherNet/IP devices to this infrastructure and then utilising the time-slot mechanism of Sercos III to transmit CIP messages during the time-slot allocated for Ethernet frames, such as TCP/UDP/IP. This time slot can also be used to transport TCP/IP messages created by Sercos III and/or EtherNet/IP devices or for other general purpose TCP/IP-enabled devices such as simple operator interface devices. The result is that machine integrators can mix and match Sercos III, EtherNet/IP and TCP/IP components within a single machine.
ODVA, OPC Foundation and Sercos International will provide their next progress report on these two areas of technical work in the fourth quarter of 2012, including initial guidance for implementation of an integrated machine network infrastructure. For more information on the machinery initiative in general, please read the white paper “Optimization of Machine Integration: A Shared Vision for Machinery Integration in the Manufacturing Sector,” available for download at the web sites of ODVA, OPC Foundation and Sercos International.