As more industrial devices with built-in Ethernet capabilities are introduced, networks will become more complex and crowded with signal traffic. "This will increase the need for Ethernet switches and routers with advanced functionality that can limit collisions, control bandwidth and create virtual local area networks (VLANs)," says Chris Vitale, senior product manager with Turck's network and interface division (www.turck.com).
"An advantage of today's LAN switches over earlier LAN hubs and repeaters is the presence of microprocessors in the switch to selectively direct communications from one remote device to another," explains Jim McConahay, PE, senior field applications engineer for Moore Industries International (www.miinet.com). "The LAN switch intelligently determines which remote sensors are connected to a particular LAN cable. It sends only those addressed communications back and forth, thereby blocking unneeded LAN chatter from other devices."
Industrial plants also use switches as a redundant pathway, should one LAN cable become damaged, thus restoring the system to full LAN communications instantaneously, he explains "LAN switches provide the means for the IT department to electronically isolate the LAN communications on the industrial side of the plant from the front office LAN equipment, and also from outside hackers," continues McConahay. "At the same time, LAN ports can help management to monitor the industrial side of the plant activities, data log and even communicate with their counterpart facilities throughout the world, all with security passwords. While earlier LAN hubs and repeaters shared LAN communications, the modern LAN switch selectively shares LAN communications."
Erik Syme, technical support manager at ProSoft Technology (www.prosoft-technology.com) doesn't foresee the extinction of switches and routers in industrial applications because the intelligence in the devices can drastically improve communications. "With switch technology improving all the time, we will see a greater emphasis on improving the intelligence built into switches and routers that will allow someone who is well-trained in Ethernet to make dramatic improvements to their device communications," he says.
"Ethernet routers and switches will not go the way of hubs and repeaters today because they provide industrial engineers with two valuable items, control and flexibility, whereas hubs and repeaters only provided connectivity," explains Bruce Hofmann, director of marketing, Weidmüller North America (www.weidmuller.com). "Ethernet switches provide engineers with the ability to extend Ethernet networks indefinitely via copper or fiberoptic cabling. They also, in the case of managed switches, provide additional capabilities such connecting two ports together to increase throughput, to set up self-healing networks and to monitor and manage network bandwidth and information priorities with quality-of-service (QoS) features." Routers provide even more functionality and control by giving users or engineers secure, direct access via a wide area network (WAN) to specific networks and specific devices, he adds. "This type of access allows engineers to diagnose, upgrade, evaluate or monitor a system or device from virtually any telephone line or Internet connection anywhere in the world," says Hofmann.
"Routers and switches allow intelligent routing of messages to their final destination and allow networks to be broken up into several collision domains," says Ernest Cisneros, development engineer, Ultra Electronics, Nuclear Sensors & Process Instrumentation (www.ultra-nspi.com). "They have become a standard network building block; they're simply more efficient. Any future network devices will probably be variants of these."
"Given the decentralized nature of IP networks, there will always be a need to connect network edge devices and route traffic for both performance and security needs," says Paul Wacker, product manager at Advantech Industrial Automation Group (www.advantech.com). "Managed switches will continue to decrease in price, while incorporating network routing—layer 3—capabilities of routers, limiting the need for routers to extremely high-capacity network core applications."
The progression from hubs to switches and then to routers and layer-3 switches is an example of more useful functionality becoming available with less incremental cost, explains John Shaw, executive vice president at GarrettCom (www.garrettcom.com). "The added complexity and cost of higher-function industrial networking devices is often not justified today and layer-2 switches dominate, but layer-3 switches and even more sophisticated security-enabled devices will someday become relatively commoditized and commonplace," he says.
From a hardware standpoint, switches replaced hubs and repeaters for networking devices together, explains Marty Jansons, networking consultant at Siemens Energy & Automation (www.sea.siemens.com). "Routers were implemented when connecting two or more networks, as well as connecting multiple remote sites together to access the Internet," he says.
Bradcommunications 200 Series Direct-Link industrial Ethernet unmanaged switches are equipped with five-, eight- or nine-port switches and are plug and play. Other features include auto-sensing, auto-polarity and auto-crossover. Each is DIN-rail- or panel-mount and equipped with redundant, dual dc power inputs. The 300 Series of managed switches are equipped with IGMP snooping, VLAN and QoS for prioritization and support redundant ring network technology and advanced network management. Direct-Link SNMP Management Suite converts SNMP messages into OPC tags that can be incorporated into and portrayed by HMI OPC client software.