Industrial controllers integrate control functions, connect to the enterprise
When designing controls, engineers can use multiple controllers: a programmable logic controller for discrete applications, a motion controller for motion applications, and a distributed control system for process applications. Or, with advancements in controller technology, these control functions can be managed in one integrated control platform. The technology advancement that made this possible was a backplane providing a high-speed communication path that allows multiple processors, networks, and input/output (I/O) devices to be mixed without restriction in one chassis.
Modern programmable automation controllers (PACs) use a producer/consumer model, which enables any device on the network to "produce" information for multiple "consumers," or devices. Producer/consumer communications directly embedded in the control backplane enable information to be passed simultaneously among any combination of controller, I/O, or communication modules in the chassis, offering seamless integration and faster communication speeds.
As the cost point for Ethernet continues to drop, original equipment manufacturers (OEMs) and end users will continue to drive Ethernet lower in the architecture. Until the smallest devices are affordable on Ethernet, OEMs are integrating device-level networks on the EtherNet/IP backbone to streamline configuration and maximize visibility into devices. EtherNet/IP Ethernet protocol is governed by ODVA. This approach creates visibility in the system and allows device-level diagnostics from a remote location.
An "Ethernet everywhere" approach also applies to motion control applications. EtherNet/IP, which uses standard Ethernet transmission control protocol/Internet protocol (TCP/IP), is fully capable to handle servo motion system requirements, including multi-axis synchronization and real-time data transmission.
Standard Ethernet can deliver on the highest performance demands of coordinated motion-including multi-axis synchronization and real-time data transmission-as well as of the integration of plant information services, all on the same wire, at the same time. EtherNet/IP is the prime example of using unmodified Ethernet to meet the 100 axis/1 ms target for coordinated motion control across multiple controllers and multiple variable frequency and servo drives. Two technologies have been developed for EtherNet/IP to achieve this goal: CIP Sync (IEEE 1588 Precision Clock Synchronization mapped into the CIP object model) and CIP Motion (a set of application profiles designed to allow position, speed, and torque loops to be closed within V/Hz, vector, and servo control drives).
Curt G. Joa Inc., an OEM, leverages EtherNet/IP for a 150-axis machine, demonstrating the Ethernet protocol’s ability for real-time data transmission.
Motion control can be placed anywhere in the infrastructure without physically isolating the traffic from other forms of traffic on the wire. In terms of traffic, it can be EtherNet/IP (where all network capabilities such as motion, synchronization, redundancy, and safety are available in all segments of the network) or nonautomation-related data streams, such as video surveillance, virtualization, collaboration and video conferencing, auto-identification and radio frequency identification (RFID), with subnets for logical sub-system isolation that are configured through virtual local area networks (VLANs). With other communication protocols, high-performance capabilities are isolated on a physically separate Ethernet network segment from the backbone Ethernet.
Controllers, future-proof networking
Using standard Internet protocol (IP) network technology, EtherNet/IP offers the best pathway to a converged network architecture, helping manufacturers streamline control and information flow to achieve plantwide optimization.
– Paul Brooks is business development manager, Rockwell Automation; edited by Mark T. Hoske, content manager, CFE Media, Control Engineering, firstname.lastname@example.org.
- PACs eliminate the need for separate discrete, motion, and process controllers.
- Controller design can enable multi-axis control.
- Industrial Ethernet eases and widens communications and allows diagnostics.
Could control platform simplification ease your control design challenges and lower lifecycle costs, while adding benefits such as diagnostics and more direct communications?
The "Ethernet everywhere" concept was explained in Control Engineering in a 1999 cover story.
See related June 2015 Control Engineering article on controller selection below.