On the application layer, EPL has also been combined with widely used, well known CANopen device profiles. This approach was undertaken because CANopen functionality is well defined and broadly supported. Ethernet on the factory floor potentially integrates motion control and field device control on a common network, but in order to accomplish this, a wide range of field devices from multiple suppliers must be available.

The Powerlink group worked closely with the CAN in Automation (CiA) group to adopt the CANopen application layer and device profiles, such as DS402 that describes the operational behavior for positioning drives.

Safe and secure

A major advantage of EPL is that it provides visibility for all devices on the network. It’s even possible to transfer data to standard applications such as databases and process control systems. This allows any device to be monitored, configured, diagnosed, or upgraded from any accessible network point.

It’s also possible to route devices through the IS infrastructure. However, access from any network, if exploited by hackers, could be a weakness. To overcome this, EPL operates as a protected segment. It will connect to a non-deterministic Ethernet network via a gateway/ router device, which acts as a defensive barrier against attacks with features such as MAC (Media Access Controller) address filtering and a built-in firewall.

EPL has clear barriers and only users with dedicated rights get access to real-time domains, so that real-time characteristics remain stable, independent from the network load.

For security as well as standards purposes, and to ensure that EPL fits the needs of automation network topologies, it was designed to comply with numerous international and safety standards, such as IEEE, IEC, and others.

Application advantages

Today, numerous plants are updating their control systems and employing EPL networks. Communication is often between an operator HMI terminal, a controller, and various devices that control equipment in the plant. An Ethernet touch screen becomes the primary interface for operators to monitor the system. Controllers are programmed and coordinated to work together to ensure the process is supplying the proper demand and all equipment is getting along. Reactions occur in fractions of a second, and the EPL system ensures that all communication takes place quickly.

In implementing EPL along with motion control into machinery, designers often find significant hardware savings from reduced wiring and the ability to use a single motion controller. Cost savings are also realized because build time is faster and commissioning is simpler. Estimated hardware savings due to reduced wiring of EPL are as much as $130 per axis. Factory and machine costs are also reduced.

On the factory floor, machine response has improved, and throughput has increased. By splitting the centralized controller’s coordinating tasks into small, decentralized tasks in the drive, performance improves due to reduced network and CPU load. Easy to use, high-level programming languages available in localized drives reduce what could be an intimidating software project to a predictable task.

EPL has also unshackled servomotors, in many cases, letting them replace pneumatics and hydraulics. Servomotors have always been fast enough, but have been limited by the number that could be connected to a single motion controller. With EPL, the number of axes inside a machine is now determined by the maximum allowed number of nodes and network bandwidth.

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