Ethernet in Motion

	Baldor NextMove e100 Motion Controller supports the ETHERNET Powerlink protocol.

A move to Ethernet as the technology solution for machine control networking is gaining momentum. Use of Ethernet communications for factory data networking, HMI communications and I/O control has already become a de facto standard. But now, there is a strong trend toward standard Ethernet to integrate high performance motion control into the automation process.

Overcoming Roadblocks

Standard Ethernet, while powerful, requires techniques for circumventing data collision. Multiple devices can connect to the same Ethernet network through a hub or switch. Devices or nodes on the network can communicate any time the network is clear. However, two or more devices accessing the network at the same time can result in corrupted data. Devices monitor the bus for this situation and, if detected, wait a random amount of time before retransmitting. Eventually a device will have sole access to the network and is able to transmit data. This data collision and random retransmission of data makes standard Ethernet non-deterministic, and a poor choice for real-time control.

One solution that overcomes this technical deficiency is ETHERNET Powerlink, which provides deterministic real-time performance by extending IEEE 802.3 Ethernet with a mixed polling and time slicing mechanism. The protocol guarantees time-critical data transfer for real-time data (such as motion control) within very short and precise, configurable isochronous cycles. Networked nodes are precisely synchronized in the microsecond range, and transmission of less time-critical data is reserved for an asynchronous time-slot.

Ethernet-based Automation Solution

The success of ETHERNET Powerlink is linked to its openness and availability. Since it does not require custom chipsets or ASICs, this software-only protocol uses standard chips that can be purchased from a wide choice of suppliers worldwide. The protocol has been developed from the field device up which allows for seamless integration with IT systems, communications to drives and sensors, and even Internet access to devices on the shop floor for remote control and diagnostics. Up to 240 devices can be connected on the same network, and multiple networks can be precisely synchronized using the IEEE1588 Real-time Clock Synchronization standard.

Proven Results

	MicroFlex e100 drives, I/O, sensors and absolute encoders can be added to the network and controlled using the Mint® programming language.

ETHERNET Powerlink also provides the motion performance needed for demanding applications such as packaging, fabrication or machining where equipment utilizes numerous servo axes. In one such application, involving over 15 servo motors and six different tools, the challenge required combining the axes into a single operating set up while automatically moving the items into place without shutting down or pausing upstream stations feeding the machine. Using ETHERNET Powerlink and decentralized motion control, critical axes are updated every 250 microseconds while secondary axes can be controlled at slower rates.

This method improved the machine throughput by over 200 percent up to 50 feet per minute, while maintaining tolerances to less than 0.04 inch. Baldor's brushless servomotors (BSM Series) provided fast, accurate positioning. By combining benefits of ETHERNET Powerlink and decentralized motion control, the machine achieved unprecedented process accuracy despite the large number of axes. The new machine produces higher quality parts and has lowered operating costs. Set-up time and scrap is reduced, and overall machine flexibility has increased.

Test your knowledge against Baldor's motor experts at http://rbi.ims.ca/4915-506