Key points
New developments in automation systems and industrial IT are the key technologies underpinning the concept of Integrated Industry. However, only when the field level is included will the claimed benefits materialise. This article shows how this challenge is being addressed by the development of flexible connectivity solutions which are consistently based on IT standards.
Real automation data, which provides an objective view of the manufacturing processes and which is the basis for every optimisation, is only available at field level. All the higher-level layers of the traditional automation pyramid only consolidate the field-level data and, in doing so, very often destroy its chronological order.
As a result, it loses any relationship to the actual process: something which is necessary for functions such as observing critical conditions as part of a status-oriented maintenance program or for efficiency optimisation.
In order to manage data traffic at different communication levels, the data must be in a pre-processed form. For Integrated Industry to be successful, it is of key importance that it moves forward into the field level.
Fieldbus systems
With the introduction of fieldbus systems, the recording of sensor data is decentralised as sensor-actuator boxes with fieldbus connections are shifted into the field. A central control system then queries these boxes periodically. Knowledge of the significance of the sensor data is typically stored in a PLC.
As a rule, the sensor is not intelligent – it merely measures. Communication allows exchange of a digital or analogue value, and analysis of this data is therefore meaningful only for the control system. Integration at the management level is difficult to achieve. The traditional fieldbus rules have not changed at all with the introduction of Ethernet as the physical layer for the fieldbus.
Inclusion of the field level in a fully Integrated Industry system only works on the basis of standards. If one considers the volume of Internet-enabled communications devices available today and relates it to the number of automation devices, the automation devices make up less than 1% of the total.
This means that new fully integrated automation devices must be compatible with the existing IT standards on which the remaining 99% of (non-automation-relevant) devices are based. True emancipation for field devices will be achieved only when they are completely and equally integrated into the Internet environment.
However, this is not sufficient for automation devices because more industry-specific requirements must also be fulfilled, and they too must also be standardised.
The need for new field devices
This means that new field devices are required for integration into the Internet environment: devices which act not only as slaves of industrial control systems, but also as masters.
This concept also changes how these devices communicate with the IT level. Specifically, this communication must be possible via other channels than just gateways, something that makes these new field devices capable of more than their predecessors (Fig.1).
The foundations for this approach have already been laid with the decentralisation and modularisation of field devices, with high-performance computing available in very compact configurations to allow the integration of relevant services.
With powerful and compact electronic modules, field devices can now pre-process and interpret the relevant information without overloading the infrastructure with large quantities of data.
For example, it is not necessary to provide regular information about a system which is working correctly: information about a deviation from the target specifications is much more important.
The combination of the fog computing approach with the use of intelligent field devices now allows constant monitoring that will not overload the infrastructure with the quantities of data that arise.
The importance of standards
To break new ground, Integrated Industry must be consistent in its use of standard IT technology. This simplifies the integration of the industrial automation infrastructure with the IT business applications within the enterprise.
However, the use of field devices in automated environments requires functionalities that extend beyond compatibility with IT standards. The various requirements in terms of the sensors and actuators used necessitate a flexible and modular structure. Consistent use of open IT standards is thus crucial.
Cyber-physical systems
The result for customers is a new Integrated Industry device that can be integrated easily in IT applications such as ERP and MES. Furthermore, all the state-of-the-art interfaces to the Smart Object will be provided. The new Integrated Industry device will thereby forge a link between the object and the cyberworld and consequently act as the central component in a cyber-physical system (Fig.2).
Ethernet developments
The key demands made on automation are high performance and determinism: the factor that provides a guaranteed response time to an event. This in turn provides an accurate date stamp which allows the control system to differentiate between cause and effect and to respond accordingly.
Standard Ethernet does not offer this determinism by itself, because it is based on statistically distributed network access in which the performance falls as the load on the network rises. This is particularly critical for fast and synchronous drive regulators, for measurement and test facilities, or when synchronising networks with, for example, wind energy in-feed.
Fast Tracking Switches (FTS) are active network components that transport automation frames or specially labelled frames preferentially: in effect, they switch on a “flashing blue light” that holds other frames back and thereby prevents congestion.
The Ha-VIS FTS switches guarantee that the preferred frames always arrive at their destination within the time calculated, irrespective of the load on the network. In this way, the Ethernet communication solutions achieve the same performance as deterministic field buses.
The new Ha-VIS FTS switches support the Precision Time Protocol (PTP) in accordance with the IEEE 1588v2 Standard, even with a hardware time stamp, and achieve an accuracy of within 0.1 µs.
They can be operated as a boundary clock or a transparent clock, and can therefore assume the role of master or slave, allowing all the participants in time-critical applications to be synchronised and high speeds in automation to be achieved (Fig. 3).
Summary
To summarise, the advance of Ethernet at the field level reduces media discontinuity, and enables accurate synchronisation of networks with the standardised PTP time protocol. This process is realised in the Ha-VIS FTS: a universal Ethernet switch that enables the construction of a deterministic Ethernet system in different automation environments.
