Cloud connectivity options drive digital competition Cloud connectivity concepts are critical for production automation. Modern industrial networks need to feature more than only high performance and high availability, but also a sufficient level of flexibility to support both present and future IIoT network configurations and solutions. A KEY BENEFIT OF THE INDUSTRIAL INTERNET of Things (IIoT) lies in the collection and analysis of data from the field level employing appropriate systems and algorithms, e.g., for predictive maintenance and its link to production planning. As a result, new strategic competitive advantages can be developed. However, in order to tap new relationships and correlations, as much data as possible has to be transmitted to the cloud with minimal retrofitting costs for existing installations. The direct connection of sensors and cloud often fails because the vast majority of field devices lack suitable communication properties. For a connection to the IIoT, certain transmission parameters must be able to be set, which determine the semantic context, on the one hand, and the concrete communication on the other. For proper semantics, a machine-readable description of the sensor properties and the data points is required to not only receive the transmitted values on the cloud level, but also to be able to understand them. Thus, in addition to the actual value, a description of the device in question and its location in the plant must be supplied as well as the sensor type, value range, sampling rate and much more. For the communication, destination addresses, transmission frequency, etc. are needed. Since there is a connection between sensor and cloud in this case, certain security characteristics are necessary as well. Typical sensor protocols, such as the 4 ... 20 mA current interface, are far from meeting these requirements. PLC as aggregation level In existing installations, it therefore makes sense to access the next higher aggregation level; this will usually be a programmable logic controller (PLC). The existing sensors are generally fully connected to the PLC, since this is where the lowest level of aggregation and processing takes place. Furthermore, the PLC also offers a certain degree of semantic description via its engineering. All data possesses a defined data type and usually a symbolic name, which also provides a kind of object model through the integration into data blocks. In addition, the sensor and the PLC itself usually have logical names or location designations, which simplify the assignment of the values to their plant context. To transport the data from the PLC to the cloud, so-called IIoT gateways are used, such as the RX1400 from Siemens. Such devices run special communication software, which cyclically queries the desired data from the PLC (for example, via S7 connections) and transports it to the cloud. The major advantage of this solution is that the existing 20 industrial ethernet book 4.2018 SOURCE: SIEMENS Technology Typical configurations for cloud connectivity utilize the PLC as an aggregation level (left) or implement specialized IIoT gateways (right).
Industrial Ethernet Book 105
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