November 1, 2006
technology review | Warehouse Control Systems

Who's in charge here?

For years, the standard answer (in the DC, at least) was the warehouse management system. But nowadays, the answer is more and more likely to be a warehouse control system.

By James A. Cooke

At first glance, Koch Entertainment's DC in Port Washington, N.Y., would seem an unlikely candidate for a software or technology upgrade. Heavily automated by any normal standard, the center is equipped for robotic picking and features an automated storage and retrieval system crane for handling large orders. Nonetheless, when it went to install equipment for filling small orders of CDs and DVDs, the company also invested in more software. The software it chose is what's known as a warehouse control system (WCS); its job will be to control the equipment dedicated to the fulfillment of small orders.

It's not that the Port Washington DC didn't have warehousing software in place. It did. The center has been using a homegrown warehouse management system (WMS) to oversee inventory operations for years. What prompted the investment in a WCS was the desire to keep small orders from clogging the existing automated material handling system, explains Philip Wulff, Koch Entertainment's vice president of distribution. Now that it has the new WCS to run the equipment used to ship, manifest, pack and label small orders, the company is able to keep the two types of fulfillment operations entirely separate.

Koch Entertainment isn't alone. As the size of the average order shrinks in an era of quick replenishment and Internet retailing, many distribution centers find themselves scrambling to keep up with a flood of small orders. Often as not, a WCS turns out to be the solution. "Smaller order quantities introduce more complexity into warehouses. That, in turn, results in the need for computer support to run the operation," says Steve Mulaik, a consultant with The Progress Group in Atlanta.

Not only does today's warehouse control software have the functionality for the job, but these systems are often more affordable than other software packages. They're also faster to install and respond more quickly to the demands of daily operations. "Warehouse control systems let the warehouse handle transactions in real time," says Jack Kuchta, an executive vice president with the consulting firm Gross & Associates in Woodbridge, N.J. "WCS are part of the trend toward flexibility driven by IT [information technology] people so they can add one element of functionality without having to change the whole system."

Traffic cop for the DC
Part of the warehouse control systems' attraction is that they help lighten the load of a DC's existing warehouse management system or even enterprise resource planning (ERP) software, a general business application that also oversees manufacturing and finance.

Though originally marketed as a "best of breed" system with limited functionality, the warehouse management system has, over the years, become the DC's jack of all trades. Along with traditional tasks like inventory management, order fulfillment and shipping, today's systems may also handle forecasting, demand planning, slotting and even labor tracking. "WMS gets involved in business issues ... that aren't related to the work being done on the warehouse floor," says Sam Flanders, president of, a material handling consulting firm located in Portsmouth, N.H.

Because they're already handling so many other tasks, WMS packages often don't contain the code needed to command complex material handling equipment. And even if they do, they're generally not nimble enough to respond quickly to transactional requests. "When you have a highly automated building, the product flows are so customized that it's not feasible to use a warehouse management system because decisions must be made in real time," says Mulaik. "WMS are not built for speed," adds Stephen Martyn, chief executive officer of Glen Road Systems Inc. (GRSI) in Conshohocken, Pa., the company that supplied the WCS for Koch Entertainment's distribution center.

That's where the WCS comes into play. Warehouse control software is specifically designed to serve as a traffic cop for machines and equipment in the warehouse, coordinating the various subsystems that handle product flow. "The WMS guys are about moving information on logistics and transportation," says Martyn. "WCS is down in the dirty world of PLCs (programmable logic controllers) and subsystems." The WCS, for example, might tell a diverter on a conveyor to direct a case down a specific chute, instruct a robot to pull a package from a storage rack, or signal a label system to stick a label on a package traveling along a conveyor belt. "It coordinates all the work on the floor," says Flanders. "It tells the system what work to do."

WCS in the middle
That ability to control an array of subsystems has become a major selling point for WCS. As technology prices drop, more DCs are going for the "add-ons:" pick-to-light systems, radio-frequency identification technology and voice-directed picking systems, for example. And each of those add-ons requires software to link the equipment to a host computer. All too often, however, companies find that their WMS or ERP system isn't capable of running add-on equipment. "People are putting in ERP packages and they're finding out that when the vendor said we had everything—they don't," says Mulaik.

What's more, the vendors may be reluctant to remedy the situation. In many cases, ERP and WMS vendors are not inclined to make modifications or additions to their software packages to run these bolt-on systems. And even when WMS vendors are willing to write the special code to interface with, say, a voice system, it can be very expensive. Small wonder that companies that find themselves in this situation often turn to a WCS. "It's simpler to deploy and less risk to a company to buy a WCS," explains Flanders of

In effect, the WCS sits between the host system—like the WMS—and the add-on equipment. "WCS is technically 'middleware' between the WMS and ERP systems and voice systems and automated conveyors," says Kuchta of Gross & Associates.

But today's warehouse control systems are much more than just an interface between the WMS and the equipment. They can be programmed with the logic to act on the information from the host system and then devise instructions to carry out a specific set of tasks. "While the WMS manages the overall activities in the operation, the WCS software executes the material flow dispatching and routing while it makes storage location decisions as well as manages the execution of order fulfillment," says Ken Ruehrdanz, industry manager at Dematic GmbH & Co. Kg., a global supplier of logistics automation equipment headquartered in Offenbach, Germany.

For instance, the WCS might take information from the WMS on the number of replenishment orders and convert that information to specific instructions for the equipment—say, batching orders to eliminate unnecessary travel for the order selector. Mulaik notes that the WCS can also be programmed to coordinate receiving tasks or group orders together for batch picking.

As often as not, companies find that a warehouse control system can accomplish these tasks much more simply and easily than a WMS or ERP can. As an example, Mulaik cites the case of a retailer that recently installed a WCS to manage the tasks associated with its radio-frequency system. That retailer, which receives 80,000 cases a day, found that the WCS could provide a smoother user interface than its WMS could, he reports. Instead of requiring workers to go through 12 fields to enter data on cases being received, as the WMS did, the WCS was able to handle the task with one screen.

WCS sold separately
In the past, WCS were generally sold as part of a package with the equipment they controlled. Back when the warehouse control system's primary function was to direct the movement of pallets and cases along a conveyor, for example, the companies that supplied the automated material handling equipment also provided the warehouse control system. That's still the case today with many makers of voice and radio-frequency systems, which supply the WCS needed to link their equipment to the WMS.

Take voice technology vendor Lucas Systems Inc. in Sewickley, Pa., for example. Although it does not offer WCS per se, it does provide middleware software bundled into its voice system package to enable the customer to take full advantage of the technology. "We do a software application that would resemble a WCS," says Jason Wilburn, director of marketing for Lucas Systems. The application takes orders from a WMS and comes up with the pick sequence. (Wilburn notes that it can even arrange the pick sequence in the warehouse bay according to the height of the user.)

But the days when warehouse control software was only sold as part of a package are gone. Marketplace demand has led to the rise of a cottage industry selling standalone WCS packages. "WCS vendors are starting to decouple themselves from equipment vendors and becoming separate entities unto themselves," Kuchta says.

Because the WCS makers are independents, their software can run equipment made by a variety of manufacturers. In some cases, the WCS modules come off the shelf pre-built. In others, the WCS provider will configure his WCS to the client's specific needs."Nowadays most WCS installations are not custom jobs," Kuchta reports. "Most WCS are being marketed as stand-alone products having hooks into types of equipment like voice or pick-to-light systems."

Bright future
It's not hard to understand why suppliers of WCS are bullish on their future. The shift away from pallet and case handling toward the fulfillment of small orders creates a wide-open market opportunity for their systems. So does the trend among DCs to knit together networks of complex subsystems.

What's also fueling vendors' optimism is the prospect of a new role for the WCS. It's becoming increasingly apparent that in the future, warehouse control systems will not only drive equipment—but people as well. As they get smarter, WCS are beginning to take on responsibility for coordinating the activities of workers by providing instructions for picking, receiving and put-away.

"It used to be that WCS was just talking to conveyors," says Mulaik. That's now starting to change. "Warehouse control systems are no longer just for automation. We can use the WCS to tell people what to do."

About the Author

James A. Cooke
James Cooke is a principal analyst with Nucleus Research in Boston, covering supply chain planning software. He was previously the editor of CSCMP’s Supply Chain Quarterly and a staff writer for DC Velocity.

More articles by James A. Cooke

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