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DeviceNet offers a safe option for emergency shutdowns

01 January, 2001

DeviceNet offers a safe option for emergency shutdowns

The Open DeviceNet Vendors Association (ODVA) is promoting a version of its bus that could be used for emergency machine shutdown applications. The enhancement, consisting of a safety protocol running on top of a standard DeviceNet network, will allow safety and conventional devices to operate on the same network. It will also allow communications between nodes such as smart I/Os and PLCs.

"Traditionally, safety systems have relied on dated technologies such as hardwired e-stops to provide protection for machine operators," says Dave Van Gompel, a member of the ODVA technical review board. "Although reliable, these systems have not kept pace with the industry-wide developments over the years. As a result, they are expensive and difficult to implement and maintain."

DeviceNet Safety is being developed by Rockwell Automation, which developed DeviceNet before declaring it an open protocol. The new protocol will be media-independent, allowing it to be used on other networks including ControlNet and Ethernet/IP. The ODVA claims that this flexibility, combined with its cost savings, sets DeviceNet Safety apart from other safety networks.

The ODVA has applied to several European certification agencies, including Germany`s TUV, to approve the protocol for safety applications. If it gets the go-ahead, it will add the safety protocol to the existing DeviceNet specification. Van Gompel says that the ODVA wants to ensure that DeviceNet Safety complies with standards such as IEC 61508.

DeviceNet is the latest in a series of bus systems to be adapted for safety applications. A version of Profibus called ProfiSafe is being developed, as is a safety version of Interbus. In addition, there are dedicated safety networks such as the German-developed SafetyBus and the British SafetyNet.

The first DeviceNet Safety products are expected to go on sale later this year.