Ethernet Powerlink is a decentralized real-time communication system for automation and motion control, which originally was developed by B&R Industrial Automation Corp.'s Austria-based parent company, Bernecker & Rainer Industrie Elektronik GmbH. B&R's innovation reportedly helped make Ethernet deterministic for real-time industrial applications. B&R's automation products feature Ethernet Powerlink in visualization, motion control, I/O products, programmable logic controllers (PLCs), industrial PCs, and network infrastructure.

B&R gets around Ethernet's limitation for guaranteed data transmission by superimposing a "time slicing" method over the carrier sense multiple access/collision detection (CSMA/CD) mechanism of Ethernet. It cuts the transmission interval into numerous slots, making a time slot available for each device linked to a network segment. "Each network node has its dedicated time window to send data," according to B&R. This ensures that no collisions take place on the network.

"Cycle times down to 200 microseconds and jitter below 1 microsecond can be obtained," says Markus Sandhoefner, B&R's industry segment manager. He adds that another benefit is Powerlink's hardware, which is based on the standard Ethernet chipset. "We wanted a commercial solution using readily available off-the-shelf products," he says.

Applications range from injection molding to packaging machines. Originated in 2001, Ethernet Powerlink claims approximately 40,000 nodes installed worldwide. The open vendor and end-user association Ethernet Powerlink Standardization Group (EPSG) manages the technology. www.ethernet-powerlink.org

• Open standard
• Real-time data transfer
• 200 microsecond cycle time with a jitter of less than 1 microsecond
• 40,000 nodes in series applications worldwide