Last updated: 15 November 2026
Three layers of software
An automated warehouse is run by three layers of software, each with its own job:
- ERP: the business system. It holds customers, purchase and sales orders, and financial stock.
- WMS (warehouse management system): it manages stock by location, plans receiving, put-away, picking and shipping, and directs the people in the warehouse.
- WCS (warehouse control system), also called MFC (material flow controller): it controls the automated equipment in real time and decides the route of every load.
Below the WCS are the PLCs that drive motors, sensors and machines. The WCS gives them transport orders and receives status messages back.
What the WMS does
- Keeps the stock record: which product, in which quantity, in which location.
- Plans and releases orders: which orders are picked, when and from which stock.
- Manages receiving, put-away, replenishment, inventory counts and shipping.
- Directs manual work through handheld terminals and work lists.
What the WCS does
- Turns each request from the WMS into transport orders for conveyors, sorters, cranes and shuttles.
- Chooses routes and balances the load between aisles, lifts and stations.
- Tracks every load on the system and reacts when a barcode cannot be read or a destination is full.
- Sequences loads so that they reach a picking or packing station in the required order.
- Shows the state of the system and its faults to operators and maintenance staff.
WMS and WCS side by side
| Question | WMS | WCS |
|---|---|---|
| What does it manage? | Stock, orders and people | Equipment and material flow |
| Time horizon | Hours and shifts | Seconds |
| Typical decision | Which order is picked from which stock | Which route a tote takes to which station |
| Talks to | ERP and WCS | WMS and PLCs |
Where the boundary lies
The boundary is a design decision, and it differs from project to project. The most common open point is storage-location management inside an automated store: either the WMS assigns the exact location, or it only requests "store this pallet" and the WCS chooses the location. The second approach lets the WCS spread products across aisles and optimise crane movements.
What matters is that each task has exactly one owner. Problems arise when both systems believe they manage the same stock, or when neither handles an exception such as a damaged or unreadable load.
What to define before the project
- The interface: which messages are exchanged, in which format and how errors are acknowledged.
- The owner of each task: location assignment, order sequencing, stock corrections.
- Exception handling: unreadable labels, weight or size deviations, full destinations, cancelled orders.
- Behaviour when one system is unavailable: what the warehouse can still do and how data is synchronised afterwards.
- Testing: an interface test with real order data before commissioning on site.
A clear interface specification, agreed early between the WMS supplier and the automation supplier, removes the most common source of delay in commissioning.
Frequently asked questions
Is a WCS needed if there is already a WMS?
For automated equipment, yes. A WMS plans stock and orders but does not control conveyors, sorters or cranes in real time. Some WMS products include control functions for simple equipment; larger systems need a dedicated WCS.
What is the difference between WCS and MFC?
The terms are largely used for the same thing: the software layer that controls the material flow between the WMS and the PLCs. Some suppliers use MFC for pure transport control and WCS when storage-location management is included.
Can a WCS work with any WMS or ERP?
Yes, through a defined interface. The WMS or ERP keeps managing orders and stock; the WCS executes the movements and reports the results.
Who is responsible when the interface fails?
That depends on what was agreed. This is why the interface specification should state, for every message, which system sends it, how it is acknowledged and what happens when it is missing.
Control software at PBC Technology
PBC Technology develops its own PLC, SCADA, HMI and warehouse control software and integrates it with the customer’s ERP and WMS.