With manufacturers increasingly in possession of real-time machine data on one hand and strict transactional business information on the other, manufacturers are beginning to see the value of integrating business software such as an enterprise resource planning (ERP) system with control systems such as supervisory control and data acquisition (SCADA) systems. However, sitting between these are specialist manufacturing execution systems (MES), which often perform the same tasks and act as an unnecessary middlemen.

Most midlevel and senior manufacturing managers understand and appreciate the crucial role of ERP software. However, at a high level, manufacturing execution systems represent an intermediary technology between process automation equipment on the plant floor and ERP software. As a result, their use is under review by many manufacturing decision-makers. Here’s why.

New learning required

Common definitions of MES suggest that they track and document the transformation of raw materials into finished goods, providing information to help business decision-makers understand real-time conditions in their plant. This ostensibly can help organizations optimize plant processes and enable control of inputs, personnel, machines, and support services.

The problem is, most of these needs can be satisfied by modern ERP software. ERP functionality provides deep traceability for inputs through inventory- and noninventory quality management tools. Personnel are managed through human resources functions, while support services from outside the organization are handled through embedded contract management tools.

Documents relevant to these various disciplines are handled by native document management functionality that enables any document – be it a material test report or a personnel training record – to be attached to work orders, shop orders, customer orders, or production recipes for virtually any object across the application.

On the other hand, within the context of an MES, documentation refers more to detailed transaction logs than to actual documents (as are covered through ERP document management functionality).

MES in the middle

MES serves as a middle tier between ERP and equipment fitted with programmable logic controllers (PLCs); this poses a challenge on several fronts. One problem is that other systems that reside close to the equipment assets often already fill this role. From my experience, most industrial settings that would truly benefit from MES already have a SCADA system, which performs several of the same functions, including high-level process control of automated equipment and the collection of real-time operation data.

Also, unless an MES is provided directly by the equipment manufacturer, it can result in more of a consulting and integration project than a defined software solution. Most of the cost involved in many MES products comes from services rather than software. In some cases, the equipment manufacturer may require operators to buy additional specialized modules to make data accessible to external systems – modules that again can overlap with common MES platforms.

Even when it comes to acting as that middle tier between ERP and productive assets, MES will not necessarily do a better job than any other discovery tool, simply because SCADA systems, MES, and other systems speak an entirely different language from ERP systems. MES will record equipment status every millisecond or so, while an ERP system will typically need to capture defined data points at the end of each batch or production run.

The information relevant for ERP is a small subset of all information normally collected in the MES. So, while an MES collects machine data in a continuous stream, an ERP system collects machine information in an aggregated fashion in the form of inputs, outputs, material transactions, and machines times. When it comes to data flowing from an MES to an ERP system, some type of application still will be required to parse data before it reaches the ERP, separating the masses of irrelevant data from the critical few.

Cutting out the middleman while keeping control

There are two well-defined methods of monitoring and controlling real-time conditions, whether you’re looking to do so strictly at the plant-floor level or across a portfolio of distributed assets and software systems. First, when data points shared among sensored assets and supporting ERP applications are well-defined, it is relatively simple to integrate ERP data directly with dashboards containing key KPIs.

Second, when dealing with data collected via IoT-enabled equipment, an IoT discovery platform such as Microsoft Azure can be paired with enterprise IoT connectors to process or analyze data before it is sent into the ERP solution.

Neither of these approaches is duplicated with existing plant or factory automation systems you may have implemented in your company. In the few cases where an MES may still be desirable, plant managers may look to industry-specific manufacturing execution systems or those available from specific equipment manufacturers. This will help reduce the consulting and professional services component of manufacturing projects while reducing uncertainty or project risk.