A network is basically a medium to transfer data. However, networks do vary based on just how much data is being transferred. Industrial networks are networks that deal with transfer of data on a large scale from industrial IoT products in an IIoT setting.
Networks allow us to connect various devices across large spaces and enable communication between them by allowing us to transfer large chunks of data between them.
At first glance, traditional networks may seem very efficient but in reality, they actually are limited to a very small number of systems. Industrial networking solutions on the other hand are designed to cater to real time needs and the demands of a far larger number of systems.
Hierarchical Levels in Industrial Networks
In an IIoT setting, there are sometimes hundreds of IoT products and the automation systems can be very complex. This automation process is usually structured into several hierarchical levels with each level having an appropriate communication level. This appropriate communication level places different requirements on the data communications company’s network.
Sensor and actuator buses are primarily used to connect simple, discrete industrial IoT products with limited intelligence to controllers and computers. Sensor buses like ASI and CAN are designed so information flow is reduced to a few bits and cost per node is put into consideration.
Industrial networks may be classified in several different categories based on functionality and let’s get right to them:
Field Level
The field level is the lowest level of the automation hierarchy. It involves field devices like sensors and actuators. The elementary field devices are sometimes classified as the element sublevel.
The job description of devices in this level includes transferring data between the manufactured product and the technical process. Data can be either binary or analogue, or both. The values are measured over a long or short period of time.
Communication at the field level is done using parallel, multi wire cables and serial interfaces. The most popular communication standards include RS422 and RS232C. Those point-to-point communications have evolved to the bus communication network to cope with the cabling cost and to achieve high quality communication.
Nowadays, industrial networking solutions use field buses a lot for information transfer. The applications in the field level controllers require cyclic transport functions because there are timing requirements in any automation process. It is worth mentioning that these timing requirements are met. This facilitates transfer of source information at regular intervals. The data representation must be as short as possible so message transfer time on the bus is reduced.
Control Level
At the control level, information flow is less from Industrial IoT products and more from loading of programs, data and parameters. In processes with short machine idle times and readjustments, this is done during the production process. In small controllers, it may be necessary to load subroutines during one manufacturing cycle. This determines the timing requirements.
This level can be divided into two distinct levels:
Cell sublevel
For the cell level operations, machine synchronizations and event handlings may require short response times on the bus. These real-time requirements are not compatible with time excessive transfers of application programs which makes an adaptable message segmentation necessary.
Area sublevel
The area sublevel consists of cells combined into groups. Cells are designed with an application-oriented functionality. By the area level controllers or process operators, the controlling and intervening functions are made such as the setting of production targets, machine startup and shutdown.
Information Level
The information level is the top level of a plant or data communications company automation system. The plant level controller gathers the management information from the area levels then manages the whole automation system. At the information level, there exists large scale networks like ethernet WANs for factory planning and management information exchange.
