This issue of Automation World’s Industrial Ethernet Review takes a serious look at how Ethernet has begun to invade the fieldbus turf. Ethernet, and its companion standards, transmission control protocol (TCP) and Internet protocol (IP), are the corporate information technology standard, and are widely used for controller-to-controller and controller-to-server communications. It’s increasingly used for communication to the input/output (I/O) layer of automation.
A major concern of engineers who would like to use Ethernet to the I/O is determinism. Ethernet is based on probability theory. Data is bundled, in packets and the packets are scattered out on the network, only to be reassembled when they all arrive at their destination. If the network is busy when attempting to send one packet, the system just retries until there is an opening. So the logical question arises, will the packet get to the I/O point in time for the device to do what is intended, when it is intended. But, as columnist Jim Pinto points out in his column in the May issue of Automation World (p. 70), when network speeds are at 100 megabits/second and approaching 1 gigabit/second, the determinism issue typically goes away.
Follow-up Webcast
The information featured in this month’s publication will be expanded into a Webcast on June 8 with a stellar lineup of speakers, including noted industrial networking expert Dick Caro and Lou Bertha, a systems integrator and engineer with real-world experience. This will also be an excellent opportunity for you to ask them hard questions. If you don’t, I will, since I’ll be the moderator on this one. You can register for the Webcast at www.automationworld.com/webcasts.
Contents
page:2 Ethernet Enters New Field : An aging fieldbus system was causing too much aggravation for engineers and technicians at Radiator Specialty Co.’s Charlotte, N.C., factory. Networking glitches became so common that technicians created a workaround so that many of the workers on the plant floor could restart the network. Engineers turned to Ethernet for a solution
page:9 Web Protocols: Internet protocols are becoming the norm in factory automation networks.
page:15 Ethernet Products
