Maintenance Technology August 2016 - (Page 41)

AUTOMATION Choose quality components. Select high-quality, shielded CAT6 cables. When choosing an Ethernet switch, purchase from a quality supplier. As for Ethernet connectors, specify industrial-grade devices. Don't try to save a few dollars by using office-type connectors. The extra money spent will pay dividends. A dead Ethernet switch or bad connector will take your system down. Use full-duplex industrial-rated switches rather than hubs. An Ethernet switch routes the packets only to the appropriate destination. A hub spits out the data to every node on the network. Thus, a switch is clearly more efficient. These Steps Maximize Ethernet Networks JIM DAVIS OF MOTION INDUSTRIES ( has some practical advice for personnel dealing with Ethernet issues on the plant floor. He knows what he's talking about. Davis manages the company's Automation Center in Countryside, IL. Among other things, he brings 38 years of realworld electrical experience to the table and holds four U.S. patents. As a point of reference, Davis notes that Ethernet has become the de facto standard in control-system communications, and equipment vendors are increasingly including it and its variants in automation equipment. Since the protocol's formalization as a communications standard (IEEE 802.3) in 1983, Ethernet data rates have increased from 2.94 megabits/sec. to 100 gigabits/sec. A 400-gigabit/sec. version is expected in late 2017. For motion-control and time-critical applications, there's a version of Ethernet called IEEE1588. This system uses a timing scheme to insure that data packets arrive in a timely and predictable manner. Standard Ethernet is commonly referred to as TCP/IP. The four main industrial-control versions are: EthernetIP, EtherCAT, ProfiNEt, and Modbus TCP. These protocols take the regular version of Ethernet and add layers of control to allow industrial controllers to efficiently talk to each other. Standard Ethernet is not deterministic, i.e., you don't know exactly when a data packet is going to arrive. The industrial versions, however, have various means of insuring data determinism. Davis offers these best-practice tips for working with Ethernet in plantcontrol systems. Following them should lead to trouble-free service. Route cable properly. Be sure to keep any Ethernet cables well away from higher voltage and/or noisy conductors. For example, it's not a good idea to run those cables next to 460-VAC motor wiring. Always use dedicated conduits for Ethernet cables in a plant environment. Troubleshoot the system. When starting up a system, ping all of the IP connections first. Ping is a command on your PC to "find" the IP node. To ping a device, go to the "search programs and files" dialog on your PC, type in the word RUN, and press enter. The RUN dialog box will open. Type the word PING followed by the IP address you are testing. For example, if a PLC has an IP address of, type PING and press enter. If you see a dialog box with "request timed out," this means that your PC cannot find the node. You may have an incorrect setting in your device or a faulty connection. If your ping test is successful, you will see a series of messages similar to this: Reply from bytes = 32 Time <1ms TTL = 128. This message denotes that the node is on your network and can send/receive data. If you want to ping your own PC, use an address of Document your system. Document every node on the network. Include the physical name ("PLC," "PUMP DRIVE #1"), its IP address, subnet mask, and gateway address. Make sure to label the control panel with the IP, subnet, and gateway information for the Ethernet items within. This information will be critical if a component fails and needs to be reprogrammed. MT For more information on industrial-control networks, visit and the MiKnowledge Hub ( AUGUST 2016 MAINTENANCETECHNOLOGY.COM | 41 http://www.MAINTENANCETECHNOLOGY.COM

Table of Contents for the Digital Edition of Maintenance Technology August 2016

On The Floor
Accepting The Challenge
Advanced Software In The Jungle
Put Efficiency in MRO Storerooms
Rethink Overall Vibration Monitoring
Reliable Pumping Supplement
Practical Oil Analysis: Why and What For?
SAP Tips and Tricks
Maximize Ethernet
Compressed Air Care
Nurture STEM Learning
Heed Drive-Belt Temps
Internet of Things
ISO 55000
Ad Index
Final Thought

Maintenance Technology August 2016