In today's world, warehouses and distribution centers are forced to meet more demands than ever before.

To get more throughput while decreasing cycle times, more facilities are turning to the strategic use of automation for picking, conveying, storage and sortation. That reality is putting a new focus on warehouse control systems (WCS)—the software that synchronizes the activities of automated storage, picking and transportation solutions.

The strategic use of automation also means the WCS is often working tightly with warehouse management systems (WMS) that manage the inventory and direct the activities in conventional storage and picking solutions.

The system not only determines the best way to route material through a facility's automated systems, but also provides real-time control to re-optimize orders as business conditions change.

In fact, in some heavily automated facilities, the WCS functions as a WMS, according to Mike Kotecki, senior vice president of HK Systems (800-424-7365). "We have deployed warehouse control systems that can also handle small amounts of manual inventory," Kotecki says. "In those examples, the WCS is acting like a WMS."

That level of control is a new development for WCS systems.

"Ten years ago, a WCS was little more than a fairly simple stock locator system that was bolted onto the equipment control layer," says Kotecki. "It would receive order information from a host system and talk to a PLC (programmable logic controller) controlling equipment."

Today's WCS offers much more functionality. This includes the ability to: optimize the flow of goods, provide real-time visibility into multiple databases to synchronize the activities of multiple equipment systems, and communicate a high-level view of all the activities on the shop floor to other systems.

There have been other changes as well, according to Steve Simmerman, vice president of marketing and business development of Swisslog (800-783-9840).

One change is that in the not too distant past, equipment systems were islands of automation. "You had a WCS to control your AS/RS, another to control your conveyors and a third to control your sortation system or AGVs," says Simmerman. "There was no unified view of data, inventory or movement."

In some sense, that's because the requirements placed on these systems were simpler. "Today, it is a more dynamic part of the overall flow of the facility," says Simmerman.

The result is that over the years those individual control systems have been unified into a single WCS that can direct multiple subsystems to optimize the flow of inventory.

There has been one other important change. Just as WMS evolved from custom implementations to a packaged solution, WCS is also moving in the direction of a standardized package that can be customized for an end-user's needs. "A warehouse control system still lags a WMS in terms of maturity and standardization," says Simmerman. "But it's moving in that direction."

As warehouse control systems take on the attributes of warehouse management systems, the two blend together. Vendors like Swisslog, HK Systems and Daifuku America (801-359-9900) offer integrated WMS and WCS solutions. In those instances, warehouse control becomes another module of the WMS.

"For us, a warehouse management system includes inventory control and material movement on the automated equipment as well as conventional receiving, putaway, picking and shipping," says Bryan Morley, vice president of software engineering for Daifuku America. "That allows us to install either or both, depending on whether an end-user already has a WMS or their own warehouse control system already in place."

Who's in control

As companies implement more automation, a number of factors come into play as a company decides which system should be in control of the inventory.

The first factor might be whether the automation is going into an existing facility or a brand-new facility.

"If an end-user has already invested in an enterprise-wide WMS license and then decides to put in an automated storage and retrieval system, the inventory will probably reside in the WMS database," says Kotecki. "But, if they're putting in a new facility that's heavily automated, the warehouse control system will maintain the inventory record for an AS/RS."

The second question might be one of philosophy: Does the end-user consider this a WMS-centric facility with some automation going on, or is it an automation-centric facility augmented by some traditional putaway and order fulfillment processes?

"There's a different strategy when you're trying to optimize people versus optimize equipment," says Kotecki. "Understanding the difference between automated control and human control will determine which system predominates."

Another consideration is the degree of sophistication of the automation. "It is relatively easy to bolt on a pick-to-light picking system and some conveyor to a WMS," says Kotecki. "But if you have an AS/RS with an integrated conveyor, that's not something you want your WMS to optimize."

Finally, whether a company has a strong IT department may also be a determining factor, adds Morley.

"If an end-user has its own WMS and a strong IT staff that's familiar with that technology, they may want to control the inventory in the conventional systems and an AS/RS," says Morley. "In that example, the WCS becomes a load mover."

Whatever the approach, deciding whether a WMS or WCS is in control of the inventory is a question that more and more companies are likely to face in the future, as automation continues to work hand-in-hand with conventional fulfillment processes.
 
In conventional warehouses, WMS systems control inventory and direct workers.