Meat packers print and network via Ethernet

Constructive Cabling
Even though they’d decided to go with EtherNet/IP, Workman says Cryovac’s builders also knew they’d need tougher wire and connectors than those typically used with Ethernet. “Regular RJ45 wasn’t robust enough, wasn’t shielded enough, and didn’t have the good connections that BL135 was going to need in our customers’ facilities,” says Workman. “For instance, while we were developing BL135, we once used a 1-ft., Cat 5, Ethernet patch cable, but it wasn’t able to withstand the vibrations--its connections didn’t hold, and eventually the machine communications were affected.”

	FIGURE 3: ETHERNET CABLING
	BL135’s unit use Ethernet/IP and an Allen-Bradley FlexLogix processor, communicating via Lumberg’s EtherMate Ethernet cable.

Workman adds that Cryovac eventually implemented 0.3 and 0.5-m lengths of Lumberg’s industrially hardened Ethernet cable, which had the heavier jacketing and increased shielding the builder needed for its combined bag printer/dispenser units. Cryovac uses M12 connectors to get from one panel to another.

“BL135’s main panel runs two dispensers,” says Workman. “There is one man PLC, and then remote I/O points and stepper drives that communicate via Ethernet. These drives run the dispenser, set the dip rollers, and spit out the bags. The printer’s controllers are tied to Ethernet too. We even have an Ethernet modem in our panels, so we can that dial in and examine our units remotely. In fact, I just did some remote troubleshooting work two weeks ago for one of our customers in Brazil.”

Workman says all of BL135’s components are coordinated and work well together. “It’s like the machine has its own little virtual private network (VPN),” he states. “We haven’t had any communication problems. We did have some concerns at the beginning, but EtherNet/IP has worked out very well for us.”

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How to Compare DeviceNet and EtherNet/IP

Here’s a brief comparison of DeviceNet and EtherNet/IP. ODVA says its two network protocols are complimentary technologies, and that they don’t compete with each other.

Target Applications

• DeviceNet puts simple devices on a network to replace hardwiring; provide device diagnostics; and control, configure, and collect data.
• EtherNet/IP ties to plant management systems (materials and planning); controls, configures, and collects data on one high-speed network; and networks time-critical applications that don't require a user-established schedule.

Typical Devices on the Network

• DeviceNet handles processors/adapters; valves, pushbuttons, sensors, and motor starters; and also simple drives.
• EtherNet/IP manages computers, processors, HMIs, I/O, and adapters.

Geography

• DeviceNet covers a single work area or machine; has limited distance due to its controller area network (CAN)-based architecture and chipset speed and power design; and allows multiple networks to feed into and communicate across a common backbone.
• EtherNet/IP can cover an entire plant using routers, bridges and switches; allows connections between plants via high-speed data lines and satellites; but non-manufacturing networks need to be separated to eliminate unnecessary traffic.

Perceived/Actual Costs

• DeviceNet has a low perceived cost due to CAN chip costs, and its actual costs also are low.
• EtherNet/IP has low perceived costs due to commercial components; actual costs may be relatively high, however, due to point-to-point architecture and switch costs 

Parts Needed to Build a Network

• DeviceNet requires a main network cable, in flat or round media, to carry power and signal (four-wire); allows devices to hang directly on the wire or be attached to a drop cable; has connectors available in open and sealed designs; and distributes power supplies on the network based on the number of devices and power requirements.
• EtherNet/IP requires a 10-Mbaud bus configuration, including thick or thin cable in star topology; accepts commercially available routers, bridges, switches and other elements; supports 100 Mbaud configured in a star topology; and requires switches for control applications.