Industrial information technology
Industrial Information Technology (Engl. I ndustrial I nformation T echnology , in short: Industrial IT or IIT) refers to a structure level in the structure of industrial networks , which acts as a link between the automation networks in the industry and the associated office level. It helps to control and monitor data streams in the exchange between different networks and to relieve automation networks in order to increase the probability of the timely arrival of time-critical telegrams between machines / systems and their control.
Starting point and necessity
Even in the days of classic field buses such as PROFIBUS , CAN , or AS-Interface (ASi) in the 1990s, automation networks were largely isolated units from the outside. For the maximum of 255 bytes that a PROFIBUS telegram includes, for example, the available data transmission rate of a maximum of 12 Mbit / s in the PROFIBUS was completely sufficient.
Since the beginning of the 2000s, however, more and more Ethernet-based communication architectures (e.g. PROFINET ) have established themselves in industrial automation . According to estimates, they achieved a higher market share than fieldbuses for the first time in 2017. In addition to higher data transmission rates up to the gigabit range and more flexible topologies, they offer the central advantage of transmitting different protocols over the same network; such as PROFINET and TCP / IP.
Although Industrial Ethernet can send and receive at the same time, only one channel is available per send direction. If you compare data transmission with a road, there is only one lane for each transmission direction and it cannot be overtaken. The data exchange between the controller and field devices must, however, be cyclical and deterministic. This means that the data must always arrive at a fixed time. If too many acyclic telegrams such as TCP / IP load the transmission paths, there is a risk of a “telegram jam” or a delayed transmission. In the worst case, the control system and ultimately the machine / system fail.
With a view to Industry 4.0, this topic is rapidly gaining relevance for the everyday life of numerous industrial companies, as the volume of data in automation networks is continuously increasing. A major reason for this is the increased use of sensors that forward data through the machine / system network to a storage or evaluation unit. The “road” for data transmission is therefore always full, even though it is not designed for this.
As a reaction to this, it has been shown in practice that existing systems have to be "upgraded" due to growing requirements. Unplanned topologies arise out of necessity, so that a comparatively uncoordinated expansion of the machine / system networks takes place and infrastructure components were sometimes not optimally selected from the perspective of the new overall network. There is therefore a need for firmly planned structures that take into account the increasing proportion of acyclic data traffic or offer sufficient reserves and still remain affordable in terms of costs and administration effort.
Structure concept
A possible structural solution is the introduction of an intermediate level where networks of information technology (IT) meet those of automation (operational technology / OT) - industrial IT (IIT) .
The distribution of tasks is as follows:
Information Technology (IT) .
IT encompasses the control, processing, storage and backup of data including the hardware and software used for this and thus forms a generic term for all processes in the company that are related to electronic data processing. IT management addresses the control of IT processes in a broader sense in order to guarantee the processes in the company and to achieve goals.
Operational Technology (OT):
Operational Technology (OT) refers to hardware and software that are required for the control and regulation, monitoring and control of machines, systems and processes. In the past, operational technologies were only seen as industrial control system technology that communicated in closed systems with proprietary protocols.
With the advent of Ethernet-based communication in the OT area, IT / OT convergence is developing, which represents a new challenge.
Industrial Information Technology (IIT):
It acts as a link between the IT and OT areas. With their help, data from the OT area is obtained and transported to the IT that is not directly related to the machine and system control, but is of decisive importance for process control and optimization, e.g. B. Quality monitoring / evaluation, logistics, material flow.
The structural concept provides for the acyclic data traffic from applications such as printers, surveillance cameras, energy management, ERP programs or quality assurance systems to be shifted to the IIT level. Only the cyclic data traffic required for the automation processes then runs in the OT network.
Switches as an essential infrastructure component - classification and selection
With increasing networking and growing data volume, the demands on the infrastructure components also increase. In Ethernet-based networks, which represent the basis for end-to-end networking in accordance with the Industry 4.0 vision, these are primarily the switches. Your original task and thus the minimum requirement is the distribution of incoming telegrams to the appropriate recipient. Therefore, they must be prepared for a higher network load due to the growing data volume. For example, PROFINET switches are certified by the user organization Profibus & Profinet International (PI) according to so-called netload classes - depending on the continuous load they can withstand without functional restrictions.
With a view to the proposed structure of the subdivision into IT, IIT and OT, switches can be classified as follows according to the model from IT, depending on the intended additional scope of tasks:
| level | Layer | Features / function |
| IT | Core Layer Switches | High data transmission rates, highly redundant forwarding |
| IIT | Distribution Layer Switches | Routing, filtering, QoS guidelines |
| OT | Access Layer Switches | Connection of end devices and servers |
Source: Own illustration based on Wikipedia.de
While unmanaged switches only distribute data, managed switches also provide valuable information for network diagnostics - for example port statistics. These provide information about the port-related network load, incorrect or rejected telegrams (discards), for example. The latest generation of high-performance switches have additional onboard diagnostic functions that are essential for use in the harsh production environment: for example, monitoring of leakage currents on the screens of the connected data lines. There are also switches with integrated routing functionality that connect different networks.
Critical discussion of the IIT concept
Advantages:
- Need-based infrastructure instead of oversizing: The OT network is relieved of "bulky" data traffic (e.g. TCP / IP telegrams). This reduces the probability that time-critical telegrams will not arrive. In addition, the demands on the performance of the infrastructure are not increasing so rapidly, so that the costs for this remain manageable. High-performance, gigabit-capable infrastructure components are only required in the IIT area.
- Preservation of structural flexibility: The central connection to the IIT infrastructure makes it easier to make modifications to OT networks and extensions and to integrate them into existing systems. If the various OT networks were to be connected directly to the IT, compatibility would first have to be ensured in each individual case.
- Consistent concept with central maintenance: Instead of several OT networks existing next to one another, which all have to be monitored separately, the IIT brings them together centrally and thus enables their scalable monitoring from a single point. If required, IT can access this data in a targeted manner without causing unnecessarily active data traffic in the OT networks.
- Sovereignty remains the same for the operator and infrastructure: Without a fixed technical delivery specification (requirement specification), the respective machine builder is responsible for choosing the switches and the structure of the machine network. With the introduction of the IIT level, which extends as a permanently installed infrastructure into the hall network of the operating company, the operating company retains the upper hand over its critical infrastructure for production, logistics, etc. - even with different suppliers.
- Better separation of responsibilities: Most of today's maintenance staff have extensive knowledge in the areas of mechanics or electronics, but not in dealing with increasingly complex networks. Since there is often a lack of time and money for appropriate training courses, this area is usually neglected and people only react. This is why it is important to have permanent persons responsible for the administration of the IIT and OT networks who are trained accordingly or have the necessary knowledge.
- If the switches used in the IIT level have integrated routing functionality, there is no need for a separate device - the switch functionality required anyway can be combined with the task of the router in a network-specific manner.
Disadvantage:
Competence wrangling: As soon as something is called "network", it is automatically assigned to the IT area of responsibility in many companies. It is true that there is extensive experience in this area in the construction and structure of networks, the handling of switches as data crossings and data processing. However, topics such as bus cycle times, real-time communication and machine control are not part of information technology training. At the IIT level, the interests of the two “worlds” IT and OT must be brought together. For example, in IT, the arrival of the data at a certain point in time has a lower priority than IT (there are no hard requirements for jitter, incorrect telegrams are not that critical). here the integrity and connection security with regard to data communication are the most important assets. At the OT level, on the other hand, there are increasing demands for real-time data communication and delays of just a few milliseconds can lead to serious quality losses in the production process.
In conclusion, it should be noted that the IIT is not a panacea and cannot be laid as a rigid template over every OT network and its connection to an IT network. How sensible their introduction is must be checked in each individual case, depending on the number and extent of the OT networks, the desired functionality and the resources available for setting up such a level.
See also
Web links
- The SWITCH - the professional in the network | Technology explained simply , what is a switch and how does it work? Basics and requirements in the explanatory video
- PROFINET - the film | Technology explained in simple terms , Basic functionality of automation technology