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Ethernet Powerlink servo system goes on show

03/18/2005

t the recent Machine Builder exhibition in Birmingham, UK, demonstrated the potential of the Ethernet Powerlink (EPL) protocol with a 12-axis system performing interpolated real-time motion control. At the heart of the demonstration was an EPL-equipped variant of Baldor's MicroFlex single-axis drive.

The demonstration showed 12 axes of Ethernet drives performing real-time interpolated motion, although the EPL technology has enough real-time speed to control up to 16 interpolated axes and many more loosely-coupled axes. EPL will support up to 240 devices such as drives, I/O devices, absolute encoders, and gateways.

Loosely-coordinated axes can be controlled using a CAN-in-Automation positioning drive profile, which reduces the load on the host motion controller, allowing simple commands to activate remote functions such as absolute or incremental moves, changing target positions on the fly, and performing homing sequences.

The new approach is said to simplify system building and commissioning - through reduced wiring and improved machine performance - at a similar cost to existing hardware.

The EPL-equipped MicroFlex drive will be available beginning in April. It includes a dual-port Ethernet hub interface to support daisy-chained drives. There is also a CANopen interface to provide a low-cost means of adding remote I/O or other components. The initial EPL MicroFlex will offer a choice of single-phase drives capable of delivering continuous output currents of 3, 6 or 9A.

Discussions with machine-builders have highlighted simpler wiring as a major benefit. "You only need a single Cat 5e shielded cable for each node, replacing numerous digital and analogue signals and fieldbus communications to each device," says Baldor's David Greensmith. "Machine-builders that we are talking to have picked on this attribute as a major saving, telling us it will remove as much as €100 per axis in terms of reduced cabling costs, along with the associated savings in design of wiring diagrams and assembly labor."