DeviceNet is not Dead
People often imagine industrial automation as vast production lines, raw materials entering one end and, through a sequence of loud, dynamic operations, widgets or automobiles rolling off the other. What they don’t see is the sophisticated infrastructure—controllers, diagnostic equipment, and connectivity—integrating production to form a reliable network. Unlike typical office networks designed to manage information like sales orders, web pages and emails, industrial networks are engineered for precision control of machines. When we send a document to a printer on the office network, we don’t care if transmission takes 5 milliseconds or 50 milliseconds. On a production line, where quality and efficiency rely on precise timing within tight tolerances, every millisecond counts.
Rockwell was among the founding companies to pioneer fieldbus networks. Designed to be a low-cost, real-time, device-level bus architecture, DeviceNet defines a standard device object-oriented software model for communication between industrial controllers and I/O devices. DeviceNet simplifies wiring and installation by transmitting power and signal on a single cable. Users can customize their control architecture from highly distributed to highly centralized. Arguably the most open automation network in North America today, DeviceNet links literally millions of devices.
Overly exuberant pundits prematurely declared DeviceNet dead—and EtherNet/IP the rising champion in automation control. Unlike EtherNet/IP, DeviceNet was never designed to be plug-and-play or a data rich environment. It was developed for interoperability among different manufacturers when transferring data between controllers and field devices using industrial network protocols. Robust engineering makes DeviceNet uniquely suited for environments with EMI, noise and vibration. As a secure dedicated industrial control system, the risk of tampering is low. An efficient network, DeviceNet transfers machine data without excess overhead.
Despite media buzz, DeviceNet remains a mainstay platform. Recently I toured one of the world’s largest agricultural operations processing corn into usable goods—a single kernel corn contributes to making 27 different products from starches to fructose to food we eat. Operating 24/7/365 the sprawling multi-building modern manufacturing complex relies on DeviceNet.
Admittedly, DeviceNet is not without its share of quirks. Not all technicians were well versed in best practices when many DeviceNet systems were installed. While a relatively forgiving network, issues must be addressed as systems age and expand. Over time, cables fray, connectors succumb to vibration, and power systems can falter. After a decade or more in an industrial environment it’s not unusual for power supplies and other components to wear out. Voltage may appear steady, yet surges occur or power intermittently drops into brown-out. Persistent problems can ultimately lead to unplanned downtime, swiftly sapping productivity and profits. One example I saw firsthand at a major automotive plant’s robotic paint application. At any given time, they may have a half million dollars worth of paint loaded. An outage can delay critical production schedules and result in costly product loss.
Whether food, packaging, material handling or automotive, plants trust DeviceNet to keep production lines running. What they don’t want are surprises inherent with any network—intermittent power loss, flexing cable, cracked sheathing, cable that was never properly shielded, or loose screws from vibration, all of which can crop up in established systems, and any one of which can deteriorate the integrity of a fieldbus network.
Increasingly, customers are proactively seeking better methods to identify and prevent problems. Better DeviceNet tools are available to simplify and ensure proper installation and certify new machinery—tools that can make the daily grind easier for technicians on the plant floor. Molex offers among the world’s most user friendly diagnostics. Brad® network diagnostic tools for DeviceNet industrial networks use high-speed data sampling to predict system faults, without interrupting operations or risking an unplanned shutdown.
NetMeter™ provides a user-friendly handheld device that diagnoses multiple DeviceNet operational variables in a health index, clearly displaying each fault condition and source. A dedicated electrical testing device, NetMeter connects directly into the network, while machines are fully operational. No need to shutdown or risk of system crashing. Additionally, the NetMeter doesn’t require programming or configuration. Even untrained personnel can certify, diagnose and troubleshoot using NetMeter. Completely passive, NetMeter analyzes signal and power lines within seconds. Network-wide and device-specific traffic, signal voltage and power quality information is displayed on a familiar user interface. A terrific value proposition, NetMeter generates highly accurate data and statistics for real world troubleshooting of intermittent faults and even detecting marginal conditions using an extensive cross-reference of common network fixes.
The enhanced eNetmeter™ DN provides a passive, IP20-rated portable meter with greater functionality including continuous high-speed measurement (up to 100 mega-samples per second) of critical network parameters (CAN signals, power and shield voltage). The eNetmeter in conjunction with our NetAlytix™ software in a portable case makes the unit easy to use on multiple networks. While NetMeter provides 677 different readings, the eNetmeter can search and identify over 2000 diagnostic points. The eNetmeter records minimum and maximum values and means. An Ethernet port enables direct connections to download stored data for diagnostic logic and diagnostic support from a PLC or computer. The eNetmeter provides continuous readings so intermittent problems can be more readily diagnosed and data securely accessed and shared from any plant location with a connection to the device IP address.
Visit the Molex website for a free downloadable DeviceNet pocket guide. If you plan to be in Houston, please visit us at Automation Fair 2013, November 13-14 (Molex booth 1501) for a hard copy.