A Look Into Popular Manufacturing Execution System (MES) Software
This article analyzes some of the leading MES software in the market and describes convergence trends among them.
ANSI/ISA-95 is an international standard that defines a framework for the interfaces between enterprise resource planning (ERP), manufacturing execution systems (MES), and other control systems. According to the automation pyramid defined in ISA-95, the MES is part of level three: manufacturing operations management. Above it is the business planning and logistics area in level four; this is the ERP’s domain. Below, in level two, is automated process control (PLCs, HMIs, SCADA, IPCs, motion control, etc.).
Figure 1. The automation pyramid, as defined in ANSI/ISA-95. Image used courtesy of Achieve DE
Historically, the applications in levels two and four entered the computer, digitalization, and robotics era sooner than those in level three. Before the existence of comprehensive MES solutions, vendors of software solutions from level two or four offered modules or extensions of these solutions that fulfilled some of the needs from the operations management level (three). This tendency continues today, and it has led to a market with numerous options for MES solutions, with each having different scopes and advantages. In general, the following subtypes of MES can be found:
- MES that converges more toward the IT side of businesses; these can be modules or extensions from ERP applications.
- MES born from the controls and automation side of companies; these are more oriented toward seamless integration with the production floor.
- MES conceived from the beginning as standalone products that integrate with the higher-level ERP and lower-level automation.
Examples of MES Software
German company SAP makes the SAP ERP, which is a leading ERP software. The latest release of the SAP ERP is called S/4 HANA. It is used by many Fortune 500 companies, including Walmart, Exxon Mobil, Apple, Ford Motor, and Alphabet (Google’s parent company).
One of the oft-cited reasons for its popularity is its legacy compatibility, counting more than 45 years of a platform that continues to be supported and maintained. This can be well-suited for large companies and multinationals that need to cover all of their day-to-day processes in one centralized database. On the other hand, this extensive back-compatibility makes the user interface look and feel slightly outdated and takes away some of the flexibility to integrate with newer automation technologies.
Figure 2. Screen captures from the SAP MES software. Image used courtesy of SAP
The SAP MES software falls in the IT-oriented category. Designed as a subset of the ERP, SAP MES can tasks, such as scheduling resources, releasing work orders, managing bills of materials, and tracking production batches. The SAP MES can be integrated with the SAP ERP, and it is a useful tool for product traceability across the entire supply chain.
However, even with the plant connectivity features enabling OPC UA compatibility, SAP MES does not offer a complete solution in highly automated processes. Its focus is more on financial transactions rather than discrete production events. The more complex the PLC- or IPC-controlled systems and equipment, the more visible the limitations are. SAP MES can be a good solution for high-volume manufacturing systems with little or some automation that does not require extensive bidirectional integration with the floor-level control systems.
First released in 2019, the Siemens Opcenter is a relatively new entry to the MES arena coming from the world’s largest industrial automation company. Backed by a vast experience and catalog of automation products, the company sees Opcenter as a natural progression step within their business.
Figure 3. Presentation of the Siemens Opcenter MOM. Image used courtesy of Siemens
Siemens does not call the Opcenter an MES, but rather a MOM (Manufacturing Operations Manager), highlighting its focus on the manufacturing processes. Referring back to the ISA-95 pyramid, the Opcenter is one of the best examples of a product born from the controls side of the industry and, thus, is capable of seamless integration between levels two and three. However, as an inverse-parallel to the SAP ERP, the Opcenter offers integration to other ERPs to a limited extent.
The AVEVA MES originates from the well-known Wonderware platform. Wonderware was the first Windows-based SCADA system, a groundbreaking development in the early 1990s. Wonderware was part of the company Invensys PLC, which Schneider Electric acquired in 2014. Then, in 2018, AVEVA and Schneider Electric completed their merger, with the latter retaining majority ownership.
Figure 4. A depiction of how AVEVA MES works within a control system. Image used courtesy of AVEVA [PDF]
Thanks to its background as a SCADA system, one strength of the AVEVA MES is its graphical user interface for control and data acquisition. Likewise, the application integrates with level two automation devices. Its ability to integrate with PLCs and HMIs across different platforms was a design philosophy since Wonderware’s beginnings. Leveraging Schneider Electric’s portfolio and AVEVA's expertise in design and new technologies, the MES solution integrates with ERP applications. Currently, the AVEVA MES can utilize some of the most common protocols to integrate with ERPs, such as web services and structured query language (SQL) stored procedures.
There are several MES types, such as IT-based, automation-based, and ERP-based. Each system has its advantages and disadvantages, depending on the company integrating an MES into its control system.
Based on the aforementioned pros and cons of SAP, Siemens, and AVEVA, which MES would you choose to implement in your company?