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Patti Engineering Solves RFID Challenges at Manufacturing and Distribution Site

By Claire Swedberg
During an RFID Journal webinar, the company described the deployment of its Siemens RFID system at a Fortune 500 company, and how it overcame challenges of water and metal presence, stray reads and the need for 100 percent read coverage.

Patti Engineering has provided a comprehensive RFID solution for a Fortune 500 company's distribution and manufacturing site that enables the firm to automatically identify where its goods are in the shipping process at any given time, based on tray and pallet status. John Shipley, Patti Engineering's senior electrical engineer, described the deploymentwhich consists of Siemens readers, antennas and programmable logic controllers (PLCs), as well as Patti Engineering's software and integrationduring an RFID Journal webinar held on May 22, 2018.

Patti Engineering is a 27-year-old provider of automation and industrial controls, headquartered in Auburn Hills, Mich., with offices in Kokomo, Ind., and Austin, Texas. The company offers solutions for the automotive, distribution and sortation industries, as well as controls for water and wastewater management and the food and beverage industry. It partners with Siemens for many of its industrial identification solutions leveraging UHF RFID technology.

Patti Engineering's John Shipley
Shipley described the challenges that the company (which has asked to remain unnamed) had faced, and the innovations chosen to work around those challenges, at the large DC and manufacturing site location. Some of the hurdles included building a system that could read tags at multiple points during the picking, packing, shipping and exceptions processes, in a varied environment in which some products contain liquid, while others do not, and in which metal could cause reflections in some cases. The system enables the company to receive data directly in its existing warehouse-management software, in order to ensure the seamless use of the RFID system.

The facility primarily serves as a distribution center, with some manufacturing taking place on site as well. Products that pass through the facility come in multiple materials and form factors, and are typically small enough to be packed into trays that are then stacked on pallets, shrink-wrapped and shipped to customers. The Patti Engineering solution begins tracking the finished goods once they are loaded onto trays for shipment.

The company has more than 250,000 high-density polyethylene trays on which the goods are placed prior to being shipped to customers; the trays are then returned to the same site. Each tray has two EPC UHF RFID tags embedded in it, on opposing sides, with a unique ID number that is stored in the RFID software. Shipley declined to name the make and model of RFID tag being used.

The tags are first read on any empty trays that might have been returned from a shipping order. The readers capture tag reads before the trays proceed through the washing process via conveyor, letting the warehouse-management system know that they have entered the facility.

When goods are packed onto the tray, packers associate specific stock-keeping unit (SKU) ID numbers with each tray, so as to build a digital record of what is on each tray. Typically, a single SKU of goods is loaded onto a single tray. The loaded tray is then moved to the palletizing area via conveyor, where the trays are stacked. Some pallets (there are more than 20,000 altogether) may contain just a single tray, while others might have up to 20. Each pallet passes another reader at this location, where its RFID number is married to the numbers on the trays.

Readers must capture the pallets' IDs by reading through their plastic material. Therefore, instead of having antennas face the tags directly, Patti Engineering placed them at an angle, enabling them to look through the pallet material in order to more effectively read each tag. The palletized products are then moved to an automatic storage and retrieval system. When a truck arrives to pick up each order, the loaded pallets are released and travel down another conveyor dedicated to distribution to trucks. A separate reader, at that point, captures the tag IDs to confirm that the products will be loaded onto the correct trucks.

Customers often request a multi-SKU order. In such a scenario, packed pallets and trays routed out of the automated system are identified using an RFID reader, and are automatically directed to a palletizing robot, which creates a pallet to fit a specific order with the appropriate number of products and SKUs. The pallets are then directed to truck distribution.

Patti Engineering's software captures the read data and transmit that information to the automation layer, as well as to the warehouse-management software layer and, finally, the software layer that manages order and fulfillment. Routing controls, Shipley says, are based on the RFID reads from Patti Engineering's software.

By embedding tags on the opposite sides of each tray and pallet, the company is able to ensure that it can interrogate those tags no matter what their orientation, or the direction in which the products are being transported, might be. "If we read upstream in one area on one side," Shipley states, "we would still be able to read if it got turned around." For example, in some cases a pallet could be loaded onto a truck but then need to come back. In this case, the company could identify what that pallet was as it returned on a conveyor.

The hardware that captures tag reads consists of Siemens' RF680R readers with four antenna ports, as well as RF660a antennas with an IP 67 rating for durability in such places as a tray wash-down area. The use of these readers, Shipley explains, provides the flexibility to install multiple antennas within a given area, such as at several conveyor lines, or to identify the direction in which an RFID tag is moving. "In this project," he explains, "it really made sense to go with the four ports."

The system also employs a Siemens S7 1200 PLC that captures data from the reader and filters it to meet the company's needs of limited data, by reducing and converting the data captured to an eight-byte Electronic Product Code (EPC) number. In some cases, Patti Engineering built enclosures for the readers as well, in order to provide greater protection in what could be a harsh environment.

There were multiple challenges with the installation, Shipley says, that required some engineering. For instance, although Patti Engineering tested the system in-house, reader performance was different onsite than it was during that testing. "It's nice to get a baseline in house," Shipley says, "but it's important to understand it can be different onsite."

This is especially true in the case of a new Greenfield site, he notes, as the facility hasn't been tested before. That required calculating not only what type of antenna was needed, but how many, the best location and the best angles. Shipley says it's a systems integrator's responsibility to communicate the risks to the customer, and to let them know that " testing and preconfiguration done offsite will likely need to be modified once onsite."

Patti Engineering used a tag diagnostic monitor onsite to count the number of reads during a given period of time, in order to ensure there is a 100 percent read rate and, therefore, enough antennas to cover the area. "A higher number of acquisitions raises the probability of successful reads," Shipley states, adding, "In this particular project, we increased coverage by simply adding and changing the location of antennas."

The company also employed an RF splitter where necessary, in order to add additional antennas beyond those allowed by the reader's four ports. The splitter does, however, reduce antenna power capacity by half, Shipley reports, and that change in read range needs to be factored into the planning. Moreover, he adds, cable lengths to the splitter and to the antenna need to be about the same length to prevent other coverage issues.

Metal and water provided additional challenges. The presence of liquid near tags (such as fluid in products on the trays) can cause energy to be absorbed, requiring a higher level of power from the reader. However, the tags on products without liquids do not need as much power from the reader, so Patti Engineering had to design the system to accommodate all possible read scenarios, based on the particular products being tagged.

Metal could provide reflections, Shipley adds, so the firm installed a urethane material that absorbs RF transmissions so the energy won't be bounced. Stray reads are another issue. At times, tags not on the conveyor could be inadvertently read. "After trying a host of different things such as increasing antenna coverage, playing around with power intensities and filtering," Shipley says, "it came down to putting an enclosure around the read point." Patti Engineering built an enclosure into which pallets passed on a conveyor, with RF-isolation curtains that fall down around the egresses.

The Siemens readers provides multiple gains for a deployment like this one, says Jeffrey Snyder, Siemens' industrial ID sales specialist. The reader supports four antennas from a single controller, he adds, or up to eight antennas with a splitter. The readers come with built-in tools to optimize antenna positioning, as well as output power selection. "They are configured with a Web-based manager," he says. "No configuration software is required."