Apply Ethernet Protocols For Real-Time Control

DN Staff

September 26, 2005

3 Min Read
Apply Ethernet Protocols For Real-Time Control

ETHERNET Powerlink, an open standard for real-time Ethernet solutions, provides a digital replacement for traditional control signals, analog demands, and feedback signals. For the advanced control of servo and vector drive technologies, ETHERNET Powerlink excels in replacing traditional drive interfaces and fieldbus systems. Powerlink drives are based on the CAN in Automation (CiA) DS402 profile for positioning drives. This results in a drive technology that is inherently more flexible and intelligent.

Within factory floor environments, Ethernet has proven successful in monitoring and managing production flow and for exchanging data between production machinery segments where timing is not critical. Dedicated fieldbus systems, however, have dominated the actual control and coordination of machinery and their component parts. That's because standard Ethernet protocols allow multiple devices to assume control of the network, resulting in data collisions. Network access and timings, therefore, cannot be predicted and hence standard Ethernet can not be applied to real-time control applications.

Flexible System Architecture

ETHERNET Powerlink solves this issue by managing each node's access to the network within allocated time slots. Data exchange between nodes takes place under control of a manager node. This approach ensures data is exchanged precisely and on schedule, achieving determinism with cycle times down to 200 muS for fast system response.

Driven by OEMs and vendors such as Baldor, ETHERNET Powerlink embraces standard Ethernet technology and infrastructure, uses standard CAT5e shielded cabling, and does not compromise standard Ethernet frames to achieve results. Unlike traditional fieldbus systems which force designers to support a variety of hardware interfaces, different physical layers, protocols, as well as service and diagnostic tools within a single installation, ETHERNET Powerlink solutions bring plug & play, connect & control capability to the lowest levels of the factory floor.

Powerlink is well suited to both PC based solutions and platforms such as Mint(R) NextMove motion control products. Mint(R) offers a high degree of flexibility to leverage real-time Ethernet. Features include advanced motion capabilities, multitasking, system events, simplified control of EPL/CANopen DS402 positioning drive axes, and common tasks such as I/O logic manipulation and HMI interaction.

Total Network Visibility

By maintaining the core aspects of standard Ethernet, Powerlink provides visibility of all devices on the network. For example, Baldor's NextMove e100 and MicroFlex e100 both feature an integrated CANopen port. Both products can manage a private network of CANopen DS401 I/O devices. In the case of the MicroFlex e100, I/O can be connected to any convenient drive. The MicroFlex e100 will manage the CANopen I/O and make this available, via Ethernet, to the motion controller where it can be used as local I/O. In essence, this allows multiple independent CANopen networks distributed around the machine managed by each drive, but controlled centrally from the motion controller.

Baldor Mint(R) devices provide further visibility of their subnet devices such as CANopen I/O. This allows any device to be monitored, configured, or upgraded from any accessible network point.

Besides a single common layer from factory management level down to controllers, ETHERNET Powerlink provides a rapid prototyping and development scheme for testing and implementing control ideas without hardware change.

A wide variety of additional system devices are available from Baldor and other vendor members of the ETHERNET Powerlink Standardization Group (EPSG).

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