Modern automation solutions aim to boost enterprise productivity by increasing product quality while decreasing production costs. The higher process complexity and production volume gets in a production plant, the more benefits are gained from automation solutions.
Business processes and manufacturing processes cannot be separately managed in integrated production plants where various production steps exist. In this kind of plants where every process is strictly related to each other, every decision made or every step taken has the potential to result in chain reactions. In such cases, a centralized automation system where shop-floor process automation, Manufacturing Execution System (MES) and Enterprise Resource Planning (ERP) solutions are present and are interconnected becomes a requirement. To describe such a centralized structure, the graphic below is commonly used. This pyramid shaped graphic is also called “The Automatin Pyramid”.
Level 0 (Field Level)
This lowest level is where all field devices and hardware stands. All these devices are directly or indirectly connected to automated control mechanism where they respond to the signals (outputs) they receive and they generate feedback signals (inputs) that reflect the actual condition on field. For example devices like motors, pneumatic systems reside at this level and are activeated with output signals from PLCs. Similarly devices like sensors, switches, instruments reşide at this level and generate input signals that are received and processed by PLCs.
Level 1 (Operational Level)
This level is also called automatic control level. PLC and DCS systems re good examples of this level. Closed loop controls, PID control, SCADA solutions, drives are handled at this level. This level is where all basic control processes are managed and is crucially important for the realization of a successful production. Solutions developed at this level are specific to process type and machine hardware itself. The technology supplier’s know-how is transformed into production at this level.
Level 2 (Supervisory Level)
This level is the connection between MES system and the ongoing production on shop level. It resides various functions such as production schedule management, material data management, product data management, machine/equipment data management, downtime management, shift data management, recipe data management, process data acquisition, reporting. These functions make the production activities easier for the shop floor crew.
Besides these basic functions, Level 2 systems may also provide more complicated functions such as mathematical models, extended recipe management, machine learning and adaptation. Especially for some processing lines, these functions are not optional but they are required. In these cases Level 2 systems are required as well.
As Level 1, Level 2 systems are also specific to process type. The complicated functions of a Level 2 system given above, require a deep process know-how. And each strip processing line has its own Level 2 system.
In some resources, you may ancounter that Level 2 is named as SCADA (Supervisory Control and Data Acquisiton) Level. But the name “Level 2” is mostly used.
Level 3 (Plant Level)
The software systems that run at this level are called Manufacturing Execution Systems (MES). This level does not focus only on one production line as lower levels do, but it does cover all production lines and share information with them. It communicates with all Level 2 systems at all times through bi-directional telegrams.
A Level 3 system may have functions such as production planning, schedule management, quality control management, material status and material transfer management, downtime management and custom reporting. But some of these functions can also be handled by and ERP (Level 4) system as well. At the design phase of all the systems and solutions, the company will decide how to and where to handle each function.
Level 3 is more focused on production data. It aims to increase the managability of production and quality control workflow and to increase the real-time traceability of production status in every possible detail. In order to achieve (almost) real-time data acquisition, a Level 3 system may have to communicate with various systems other than Level 2s, using various methods and protocols.
Level 4 (Enterprise Level)
This level is where ERP (Enterprise Resource Planning) softwares run at. ERP solutions focus on the corporate level activities (finance, accounting, human resourcs, etc.) which are not directly related to production and shop-floor activities.
Level 4 communicates with Level 3 through bi-sirectional telegrams. Level 4 does not expect receiving quick respond about real-time plant data as Level 3 does.
Let’s take a closer look at Level 2
Level 2 systems are the software solutions which run mainly in Client – Server architecture. On server side, the data are stored in a database (most probably a relational database product such as Oracle or SQL Server) and functional activities are managed by specific applications. The client side is the graphical user interfaces. There may be various numbers of client stations where each one is used by different users with different authorization levels such as system adminitrators, engineers, operators.
Level 2 application server continuously sends and receivs messages to and from Level 1 and Level 3 systems. Production production targets are received from Level 3 and are transferred from Level 1 and transferred to Level 3.
Level 2 databases do not mostly store a big amount of historical production data. Production history is preferred to be stored at Level 3.
The list of functions a Level 2 automation system can supply is listed below:
Possibility of processing wide variety of input materials with specific set of parameters.
Process specific, complex and adjustable recipe management.
Dynamic parameter calculation with the use of mathematical models.
Self-optimization of mathematical models with machine learning.
Production data storing and reporting.
Integration and data transfer with MES.
Production line downtime management.
Critical equipment management. (Equipment use history, handling of equipment change times).
The Cases When There is No Level 2 System
We can say that Level 2 system is not a requirement when the conditions below are present:
If Level 1 system is able to satisfy all automated functional expectations
If there is no need for Level 2 functions described in previous section
If the shop floor will not communicate to an MES system
In case a Level 2 system is not present,
Operator activities are performed with tools such as Level 1 HMIs, local panels, touch screens.
Production planning process is not connected to shop floor
automation. Production crew receives the production plan manually (by
email or a hardcopy document) and has to follow performed activities
Production results are reported manually (by email or a hardcopy document).
Recipe management and adjustment is handled by Level 1.
Production history and reports are managet by Level 1.
Relational production data of various processing lines are not transferred to a centralized database.
The Future of Automation Pyramid
The automation pyramid described above structures the systems in a hierarchical way. This design defines what tasks each level will perform and how data will flow between these levels. Automation systems using this method is widely used around the world and technology producers continue supplying systems based on this structure.
Thus, we might expect the revolution of Industry 4.0, focusing on decision making, easy connectivity and decentralized solutions to change the direction of industrial automation technologies and to replace the automation pyramid in a way. But it is inevitable that most of the functions from various levels of this pyramid will be existing within this new concept. Maybe not in a hierarchical way but in a distrubuted way.