The production support system is a set of activities for managing the flow of information related to production. It includes the following aspects:

• Business: These are activities that strictly face the customer and are related to the start and end of the whole process. These include order management, marketing, sales, and the budget.
• Design: These are activities related to designing the product according to the customer's needs, expectations, and requirements.
• Planning: These are activities based on planning the business and design functions of a product. They involve the working sequence, timing, storage, and supplies.
• Control: These are activities related to the management and supervision of the process production. It includes controlling the production flow and checking the quality of the production processes and products.

We can sketch these activities as a loop around the production activities managing the related flow of information, as shown in the following diagram:

For all of these, there are specific software applications for automating and coordinating the different activities. These include the following:

• ERP: For managing tasks such as logistics, production management, accounting, personnel, purchases, warehouses, project and sales management, and plant and distribution management
• Computer-aided design (CAD) and computer-aided engineering (CAE): Software tools for designing, testing, and validating the product against the specification or requirement
• Computer-aided process planning (CAPP) and MES: Software applications for automating and optimizing the planning process

This type of approach, however, might lead to the creation of automation islands that are not integrated with each other. A huge improvement can be achieved by integrating all subsystems at the company level. This can be done as follows:

• By implementing a structured design of the whole information technology stack
• By managing the flow of information between the various devices at different levels
• By coordinating factors involved in the production cycle, including the human factor, as shown in the following diagram:

However, in all production processes, there is a trade-off between the variety and the quantity of the production in terms of the number of parts or the output. Typically, the higher the quantity of the production, the less variety there can be in the production.

This trade-off threshold can be then shifted up through a very flexible production system that uses highly configurable machinery. This machinery can be easily set up for different uses and allows for a strict interaction and integration between the information systems of the production process and the support activities, as depicted in the following diagram:

CIM is a logical model for production systems that were developed in the 1990s to integrate the production processes, the automation systems, and the information technology systems at a company or enterprise level.

CIM should not be considered as a design technique for building automatic factories, but rather as a reference model for the implementation of industrial automation based on the collection, coordination, sharing, and transmission of data and information between the different systems and sub-systems by means of software applications and communication networks.

The CIM model is strongly hierarchical:

• Support activities are at a higher level than those of production.
• There is a hierarchy within those support activities.
• The business activities influence the design and planning of production.
• The production activities are also structured in a hierarchy. The automation of a production step is at a lower level than the automation of the whole machine, which is carried out by a further sequence of steps.

The CIM model is often depicted as a pyramid made up of six functional levels, as shown in the following diagram:

• Level 1—field: This level includes all devices that interact directly with the process, such as sensors and actuators.
• Level 2—command and control systems: This level includes the devices that interact directly with the sensors and the actuators, such as PLCs, micro-controllers, proportional-integral-derivative (PID) controllers, robot controllers, and computer numerical controllers (CNCs).
• Level 3—cell supervisory: In a cell, a complete sub-process of production is executed through various devices and machines that must be coordinated with each other. The main functions of the control devices placed in this level are the following:
  • The receipt of the instructions from the upper level.
  • The transformation of the lower level devices into actions and commands.
  • The collection of information from the lower levels to pass to the upper level.
  • The arrangement of information for the human supervisor, who may eventually issue commands or set up set-points or thresholds.
• Level 4—plant supervisory: At this level, the production database collects and stores the main parameters of the production process, and the coordination between the cells is carried out to implement the whole production process.
• Level 5—plant management level: At this level, the aforementioned integration between the support systems takes place.
• Level 6—company management: Typically, a company handles several plants, so at this level the information is collected from the lower levels to feed the decision support systems that help managers to plan flows of materials and finance necessary for the maintenance, improvement, and optimization of the production process.

The pyramidal shape used to present the CIM levels is suitable for a hierarchical organization in which the following occurs:

• Each level communicates directly with the upper one, from which it receives commands and sends information
• Each level communicates directly with the lower one to send commands and receive information
• Each level sends to the upper level less information at a lower frequency than that received from the lower level

This strict and mutual interaction between the different systems and sub-systems involved in the production cycle has a number of benefits. Among the most important of these are the following: 

• More efficient usage of resources through the planning of production processes
• Greater flexibility in production, as the system can be promptly and easily adjusted to conform to a new process
• A reduced processing length
• An improvement of the product design due to digitization, given the need to provide unambiguous information to digital machines and systems
• The identification, storage, and re-use of information related to the product
• An improvement in the quality of the product due to more stringent validation checks
• The reduction of stocks of raw materials and warehouses used to store finished products and any processing waste

It is important to remember that the CIM pyramidal structure is a logical representation of the factory automation world. This means that the canonical six levels can be coalesced into a simpler structure with fewer levels. From an operational perspective, for instance, the CIM pyramid is often represented in five levels:

• Field: Sensors, actuators, and hardware
• Control level: Control systems, such as PLCs and DCSes
• Supervisory level: SCADA systems, time-series databases, recipe management, production reporting, and alarm management
• Planning level: MESes, plant-wide operations, asset management, and maintenance
• Management level: ERP systems

In IT companies that provide automation services to factories, the CIM pyramid is typically simplified to a three-level structure:

• Automation control: All equipment for the automation and control
• Supervisory: Devices and applications for the supervision of the production process and the maintenance of equipment
• Production management: Applications for the planning and management of the production

Both coalesced representations of the CIM pyramid are shown in the following diagram: