Industrial Network Convergence

  • November 21, 2012
  • Feature
November 2012
By Bill Lydon, Editor
Industrial Ethernet has enabled a level of industrial network convergence to become a reality. Multiport controllers and gateways provide configuration flexibility. Many professionals in the automation industry had hoped and wished for a single industrial open architecture network protocol. This has not happened. Industrial Ethernet protocols, coupled with low cost pervasive Ethernet technology, have made the support of multiple protocols on a single controller a reality.  That capability provides the flexibility to leverage the advantages of various networks and make technology additions to existing systems. While not ideal, this trend is approximating the goal of a single industrial open architecture network. Open industrial Ethernet automation networks include Modbus TCP, EtherNet/IP, PROFINET, SERCOS III, EtherCAT, POWERLINK, IEC 61850 and DNP 3 among others.
Native Interfaces
The most effective way to integrate networks is to use industrial controllers that support multiple communications protocols and hardware gateways with native interfaces to protocols. It is becoming common for industrial controllers to natively support multiple industrial Ethernet protocols. That way, controllers satisfy a wide range of unique application requirements encountered in various industries. Controllers with native protocol support in this context means there are either standard ports on the controller or “in rack” plug-in cards to add multiple Ethernet or other non-Ethernet industrial networks. This native interface is a major advantage compared to software interfaces at a PC-based HMI that can be corrupted by software updates, require continual updates, or be compromised by other unstable applications running on those computers.
Small standalone gateways are available from a number of vendors to interface devices between industrial Ethernet protocols. These devices translate and map data between the protocols allowing application engineers to transparently use multiple network protocols to mix and match solutions to solve problems. Configuring these gateways is typically done with a software program that downloads mapping to the device. Even simpler, newer gateway devices serve up web pages with fill in the blank forms to define configuration.
Gateways are useful when adding old devices to a new network backbone or new devices to existing non-Ethernet systems backbones. In a major automation systems upgrade that uses a new industrial Ethernet backbone, gateways can be used to interface existing controllers and devices that have older network interfaces to preserve hardware and programming that is still working. This practice is particularly valuable when there are budget constraints. The other strategy is to use gateways to add newer controllers and devices to an older existing network to add improved functionality. Examples of existing protocols include Modbus, DeviceNet, Profibus, DNP 3, BACnet, CAN, CANopen, and DF1 among others.
The reality is that existing industrial plants will have many industrial network protocols and physical networking types for years – ranging from twisted pair to Ethernet. The communications flexibility of industrial controllers (that support multiple protocols and gateways) allows users to configure systems and keep plants running smoothly, all while managing budgets. Installation of a new system can be very disruptive and expensive. Controllers with flexible communications options allow users to add functionality to existing systems incrementally.

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