scope:

MES solutions must fit in with the existing IT landscape consisting of software solutions for different business tasks. MES solutions are situated between the planning level supported by commercial business software (ERP systems) and the execution level of the production process. At the execution level, automation solutions are increasingly used for manufacturing processes as well as transport and handling operations.

While the ERP level deals with the scheduling and dispatching of requirements (based on sales orders, master production schedule, etc.) and considers resources from a macroscopic perspective, the MES level focuses on the short-term, detailed planning and control of individual production orders and the related operations (microscopic perspective).

With a view to its run-time behaviour, an MES can be characterised as a real-time system. Accordingly, the time it takes an MES to respond to and to influence specific conditions is shorter than the time it takes the process to respond to these conditions.

At the MES level, the input data for planning and control activities consist of the results from roughcut ERP planning and the master data stored in the ERP system (e.g. item master, bills of material, capacity master data) as well as feedback data from the production process.

During a detailed scheduling run at the MES level, the rough planning results imported from the ERP system are broken down into individual operations and associated activities (e.g. tooling or material provision) and then scheduled while considering existing planning constraints. These planning and control activities specify which order or operation is carried out at what time (planning bucket < 1 day), what resources (work place, tools, etc.) or control programmes are used, and by what staff member. Depending on the level of integration achieved in data processing, the control data is either viewed by the operators, e.g. via production control station, or is immediately converted into control commands for the production equipment. The same applies to the processing of feedback data from the production process (e.g. order-related information such as number of units and time data, machine data such as conditions and machine parameters, or quality data such as inspection results and measured values).

Usually, the information transfer between MES and automation level implies a "change in technology". MES solutions, analogous to ERP systems, are programmed in high-level languages such as Java and are usually maintained by the internal IT department, while programming in automation engineering is governed by flow charts, instruction lists, and sequential function charts. Protocols such as OPC are available for integrating MES with the automation level.