Glossary · Industrial communication
POWERLINK
Also known as: Ethernet POWERLINK, EPL
German: POWERLINK
In industrial communication, POWERLINK (Ethernet POWERLINK) is an open real-time Ethernet protocol, originally developed by B&R and maintained by the Ethernet POWERLINK Standardization Group (EPSG). A managing node grants time slots to controlled nodes, which gives deterministic cycles on standard Ethernet hardware.
- Industrial communication
- Standards
In one sentence
POWERLINK is an open real-time Ethernet protocol in which a managing node assigns time slots to devices for deterministic cycles.
Example
A printing machine synchronizes its web-tension drives over POWERLINK, with the machine controller as managing node.
How it applies
- Engineering: POWERLINK uses a time-slot procedure: the managing node polls each controlled node in the isochronous phase, followed by an asynchronous phase for other traffic. It uses the CANopen application layer, so device profiles are familiar.
- Installation: Hubs are preferred over switches in the real-time domain to keep delays predictable. Mixing POWERLINK traffic with uncontrolled Ethernet traffic in the same segment disturbs the timing.
- Safety: openSAFETY can transmit safety-related data over POWERLINK and other networks; the overall safety function still has to be designed and validated.
- Documentation: The documentation team documents node IDs, cycle times, the device's XDD description file and whether the product acts as managing or controlled node.
POWERLINK vs. EtherCAT
Both give deterministic cycles on Ethernet hardware. POWERLINK polls devices one by one in time slots; EtherCAT processes a single frame on the fly through all devices.