Interoperability and safety issues engage ODVA

Open DeviceNet Vendors Assn. finalizes EtherNet/IP spec, moves on to safety network.

By Dave Quebbemann, President, ODVA

The Open DeviceNet Vendors Assn. (ODVA) is working hard to ensure that the DeviceNet protocol continues to expand its capabilities and offer the highest degree of flexibility and compatibility of any open network.

The finalization of the EtherNet/IP specification in April of this year is one of the most significant recent issues pursued and accomplished by ODVA. EtherNet/IP fills a void by delivering interoperable Ethernet products. That’s because EtherNet/IP is a protocol stack that extends commercial off-the-shelf Ethernet with an open, industrially proven protocol for automation purposes. At the same time, it supports common office protocols such as FTP, SMTP, and HTTP.

Based on the TCP/IP suite, EtherNet/IP uses TCP for information messaging and UDP for I/O messaging. By using both TCP/IP and UDP/IP to encapsulate data, this is the first industrial Ethernet network to provide real-time I/O control. Using DeviceNet and EtherNet/IP protocols, a machine builder, system integrator, or end user will have the capability to seamlessly route device-level information all the way through to the information layer without the need for expensive gateways or complicated data mapping.

ODVA has made available the necessary developer tools, specification, and training for EtherNet/IP. This information is readily accessible from the ODVA website.

This past summer, ODVA announced the first EtherNet/IP Conformance Testing Lab, located on the campus of the University of Michigan at Ann Arbor. ODVA labs in England and Japan will go online soon. The lab is working to ensure the interoperability of EtherNet/IP products.

To further support the seamless exchange of data, ODVA recently agreed to support the development of an OPC Data Exchange (DX) standard for Ethernet. The automation systems being developed over the last several years require the exchange of data among systems using different protocols. The OPC DX standard will provide interoperable data exchange and server-to-server communications across Ethernet networks. Support of this effort by ODVA gives users of DeviceNet and EtherNet/IP ability to seamlessly exchange data with their legacy automation systems that have networks based on other protocols.

ODVA recently announced its initiative to develop and promote DeviceNet Safety, an advanced safety network designed to meet the demanding requirements of machinery-shutdown and process–sector availability applications.

Consisting of a safety protocol running on top of the traditional DeviceNet network, DeviceNet Safety will allow both standard and safety devices to operate on the same network. In addition, DeviceNet Safety will provide communication between safety nodes, including smart input/output and programmable logic controllers.

As machine builders well know, safety systems have relied on hardwired e-stops, interlock switches, and dual-contact actuators to provide protection for machine operators at run time. Although reliable, these traditional systems have not kept pace with technology developments in the automation world. With increasingly intricate control systems and the trend toward plant-wide integration, the task of developing a safety system with traditional components becomes infinitely more difficult. Complex electronic devices such as mutable light curtains and robots further complicate matters.

During the last decade, engineers used redundant controllers, I/O, and networks as safety devices in some of the previously mentioned applications. And, once again, these systems have proven effective. The problem is that they also are expensive and difficult to implement and maintain.

Today, international standards bodies are working to define the safety of electronic systems worldwide. As a result, ODVA decided to bring its networking expertise to the safety industry.

With DeviceNet Safety, users are able to ensure safety on the plant floor without separate networks for safety and standard control. This flexibility, along with its cost savings, will set DeviceNet Safety apart from existing safety networks.

Another differentiator is that the safety protocol will be media-independent. Although originally ported to DeviceNet, industrial OEMs, SIs, and end users will be able to apply it to any network without regard to physical media, including EtherNet/IP.

ODVA is also reviewing various ways to improve the organization itself. The membership at ODVA has grown to a worldwide membership of 310 companies that are working aggressively to implement and improve DeviceNet. As ODVA evolves, it is important to recognize and understand the needs of the companies that use and/or install DeviceNet. The current ODVA charter only allows for manufacturers. In an effort to better understand the needs of users, ODVA is evaluating several options to include them in the organization. Expect this change to occur during the next six months. It will have an extremely positive impact on the membership and strength of ODVA.


  About the Author
Dave Quebbemann is president of ODVA and a member of the organization’s board of directors. You can learn more about ODVA’s work at www.odva.org.
 
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