Why do we need MES when we already have SCADA?

Blog by Vladimir Lukić, Co-Founder at 8Sigma

I have spoken recently to my colleague, an automation engineer who asked me why someone would want to bother with implementing MES when modern SCADA systems already have the functionalities such as reporting, relation database used for storage and historian with the purpose of collecting historical data.

Everything can be done in SCADA, why MES then?

I answered him by asking questions: Can you also replace ERP with SCADA? Can you implement in SCADA all the things that modern ERP includes? I didn’t get an answer from him.

The point is that we first need to understand the role of each system. 

SCADA is a system focused on controlling the production and utilizing with PLCs in real-time. Although with SCADA we can acquire information like effectiveness, product quantity, and average production speed, it still does not enable us to track the detail transformation of raw materials to finished goods through the complex series of operations and steps. 

On the other hand, the role of ERP is to track a company’s complete business process, of which only one part is the production process. ERP system does receive (via MES) data from the production process, but the amount of this information is very limited. Mainly it is summarized data important for the business process (sales, accounting, supply chain) which refers to the total amount of raw materials used in production, a total number of final products produced product quality information, etc.

ERP is designed to work with transactions. However, in the production process, there is often a tremendous amount of information exchanged in real-time that needs to be processed and analyzed in order to achieve optimal manufacturing. This is the point where we need a system capable of dealing with both real-time data and transactions. 

So here comes MES

While SCADA is designed to control the production in real-time and ERP is designed for management of the company’s business processes, MES is designed to track and collect information about each product (semi-product) through all stages of the production process. It is a software capable of operating with big data received in real-time (PLC, SCADA), while also exchanging information with the transactional world (ERP, SCM, CRM). 

MES’s purpose is to analyze and extract important information from this big data and forward it to ERP. Also, this software solution can convert work orders received from ERP to a production schedule and is capable of dispatching this schedule to the shop floor (PLC, SCADA). It is very important to properly correlate between process data and product quality and to provide and collect information in different formats from various systems. 

Therefore, as a definite answer to my colleague, why not make PCS, MES, and ERP in one system?