Ethernet/IP Brings Clairvoyance and Productivity Improvements to Network Maintenance.
Source: Bill Martin, Rockwell Automation.
Before the existence of networked, intelligent automation components, one might have assumed that the most important skill of maintenance engineers was clairvoyance. They seemed to divine the source of equipment problems, understanding their facility’s health as if it were their own.
It wasn’t magic. It was decades of cumbersome, time-consuming troubleshooting. If a motor stopped unexpectedly, engineers would have to physically suit up with personal protective equipment, go to the electrical cabinet and probe around with a volt meter to try to detect the issue. They played a real-life hybrid of the board games “Clue” and “Operation,” which challenged their deductive reasoning, threatened shocks and took time. Because very few companies supported traditional apprenticeships during the recession, when these seasoned maintenance staff retired, their knowledge of their machinery’s idiosyncrasies also left the building.
Device-level networks and intelligent components are helping today’s engineers bridge the seasoned-skills gap by offering a better way to capture equipment data, improve wiring and increase productivity.
Device-Level Networks at the Turn of the CenturyNetwork advancements in recent years make the technology of only 15 and 20 years seem antiquated. The device-level networks in the 1990s were focused on reducing hard wiring between motor control-related components, such as overload relays and starters, and programmable logic controllers (PLCs).
That focus made sense. For example, without networked, intelligent devices, engineers would have to wire eight of a motor starter’s hard wires individually to a centralized output card that would then need to be wired to a central PLC. Those wires required conduit and the resulting mass of wiring would have to be maintained.
Electronic networked devices met the need for minimized wiring, but their device-level networks left room for improvement. For instance, they required special tools to wire, and users needed to purchase a separate piece of software to configure and assign different memory locations within their scanner. While engineers received device-level data, it was clear that reaping device-level intelligence was a secondary focus of the networks. Those early device-dedicated networks had limited bandwidth because they were intended for discrete components such as push buttons and limit switches. With bandwidth limited, engineers were confined to only five or 10 parameters of a device, such as an intelligent overload relay, that might have 300 possible parameters. Further, when that data arrived, it did so in the form of 1s and 0s that had to be decoded before being understood.
The Benefits of Networking Components with EtherNet/IP
The automation world is migrating toward EtherNet/IP because the network improves information sharing, meets users’ needs for ease of wiring and is intuitively understood. The learning curve for EtherNet/IP is much shallower than those of other networks because engineers are already familiar with plugging an Ethernet cable into a computer, clicking a mouse, and dragging and dropping. It’s an easy cable set to handle, is readily available and doesn’t require any special tools.
Clearer data is more meaningful data and because the focus of EtherNet/IP is information sharing, it greatly simplifies the process of understanding data. With EtherNet/IP, the cryptic messages from earlier device-level networks are replaced with decoded messages that have meaningful names assigned to them. For example, if a pump motor experienced a phase loss, the network message would be absolutely clear in the EtherNet/IP environment: “Pump #4. Phase loss. Phase B.” The message is immediately clear. Engineers don’t have to decode any 1s and 0s so there is no room for misinterpretation. They see that they need to replace the phase-B motor fuse.
Information is meaningful on the control side of the EtherNet/IP network, as well. For example, with previous networks, engineers might code a 1 in a particular bit location to turn on their output on a Relay One to energize a starter. They needed to track what their codes meant. Now with EtherNet/IP they put a bit on the location that says Relay One, and there’s no decoding necessary. It is what it says it is: Relay One.
EtherNet/IP also eases data collection for predictive maintenance. Engineers can use historical data collection engines directly in their intelligent devices to collect data instead of using the PLC as the data concentrator, a function which traditionally required additional programming. As an example, a company might monitor and trend a large motor’s current draw information every 15 minutes as a predictive measure. If current draw creeps up over time, maintenance would be prompted to schedule an examination of the motor bearings.
Doubling Down with Dual Ports Dual-port EtherNet/IP capabilities in the latest components further elevate system performance while decreasing complexity. Device Level Ring (DLR) is a network technology that takes advantage of embedded-switch functionality in automation devices, such as I/O modules.
EtherNet/IP simplifies installation of devices with DLR because engineers can daisy-chain from one device to another. This allows a linear topology that removes the traditional necessity for an external switch that was needed in a center-point star configuration using external switches. This daisy chain, peer-to-peer architecture also reduces the physical amount and associated cost of cabling and often avoids it being routed inside trunking with other power cables, minimizing any potential electronic interference.
DLR technology also adds device-level network resilience. When a DLR detects a break in the ring, it provides alternate routing of the data to help the network recover at extremely fast rates. For example, a 50-node DLR network can recover in less than 3 ms, and the connection between the controller and the I/O device is not interrupted. Enhanced diagnostics built into DLR-enabled products also identify the point of failure, helping to speed maintenance and reduce mean time to repair.
Eased Data Access to Drive Decisions Getting real-time information at the right time and at the right levels of the manufacturing environment helps to improve just about every facet of a plant’s operations. EtherNet/IP offers engineers a more deterministic network, meaning there’s direct connection between the controller and the end device. That enables fast (within 2 ms) sharing of control information between the device and the controller. The network also eases remote device interrogation because many intelligent components now have an embedded Web server that can be accessed remotely using a simple, password-enabled Web browser.
Today’s new maintenance engineers might not have the tenure of their predecessors, but with EtherNet/IP networking their intelligent electronic components, they’ll appear to be just as clairvoyant.