Respecting real-time requirements in networked control systems requires that the network traffic respects some well-defined constraints. Any abnormal behavior, e.g. due to malfunctioning of few devices or representing a malicious attack, could disrupt the overall plant behavior. Immediate recognition of anomalies should occur, to determine the causes and mitigate the impairments. Despite hardware sniffer being ready available, deployment cost, maintenance cost and topology constrains of industrial network discourage their adoption for live traffic collection. Additionally, anomaly detection systems are typically complex solutions that demand experienced personnel, which is not generally available among plant maintenance workers. This paper presents the ongoing research activity for a simple but effective expert system that gathers network-related figure of merits natively evaluated by industrial-grade devices, acquired by standard SNMP (Simple Network Management Protocol) queries. Data collected by such a distributed measurement system are further analyzed using simple classification techniques, as the unsupervised clustering, which limit the computational burden. In this work some suitable performance indicators are addressed and the related multi dimensional clustering is discussed. Some preliminary results are provided, exploiting a reference use case designed around a real-world assembly machine.

The Industry 4.0 has led to a significant transformation in manufacturing and industrial processes, characterized by increased connectivity and widespread digitalization. This revolution is driven by the convergence of IT (Information Technology) paradigms with OT (Operational Technology) domains. Virtualization technology plays a crucial role in this integration, thanks to its characteristics of agility, scalability, and efficiency. This work investigates the virtualization of Programmable Logic Controllers (PLCs) and it is focused on the need for evaluating their performance. PLCs are essential components of industrial automation and are being virtualized to increase flexibility, reduce hardware dependencies, and enable seamless integration with IT infrastructures. This work proposes a methodology for evaluating the execution time of a benchmark program and the PLC real-time behavior. Experiments on a real use case demonstrate that the PLCs implemented in containers may be 50 times faster than the real ones in executing data elaboration, while no significant differences were observed in real-time communication. In any case, virtual PLCs are characterized by greater jitter with respect to real PLCs.

The demand for enhanced flexibility in automation systems, dictated by initiatives as the Industry 4.0 in Europe or the Industrial Internet Consortium in the United States, can be satisfied inheriting solutions of the information technology (the so called IT-OT convergence). Other than communication and cloud technologies, virtualization will play a relevant role in the next future. The use of lightweight virtualization, e.g., in the form of containers for implementing the edge computing paradigm, is a promising tool to dynamically provide services depending on the actual production needs. However, requirements of industrial automation applications are different from those of office-like counterparts. For this reason, methodologies for evaluating obtainable performance are needed. In this work, an industrial-grade framework, the Siemens Industrial Edge, is considered. A reference testbed is setup to evaluate latencies when information is exchanged between two user applications. Experiments demonstrate that round trip time in the order of 10 ms is feasible, compatible with the requirements of both process control systems and supervision applications.

LPWAN, an acronym for Low Power Wide Area Network, addresses all the wireless communication solutions aiming at maximize the lifetime of battery powered end devices by means of high-sensitivity radios and sporadic data transactions. Among the different members of the LPWAN family, LoRaWAN is an emerging solution satisfying requirements of many Internet of Things (IoT) related applications. LoRa WAN supports both public and private deployments, operating in unlicensed frequency bands. Handling critical messages, e.g., originated after emergency events in industrial plants, is out of the original LoRaWAN scope. For this reason, the LoRa-REP replication scheme was proposed to increase reliability and to reduce latency of confirmation. In this work, obtainable performance are further improved allowing frame overlaps in time and frequency, exploiting LoRa virtual channels. In particular, Software Defined Radio paradigm is exploited for implementing a proof-of-concept to be used in real-world trials. The preliminary results, supported by simulations as well, are discusses, confirming the feasibility and effectiveness of the proposed approach.

Wireless communications may be the key solution to satisfy mobility, flexibility, and scalability requirements of the Internet of Things. Particularly, the low power wide area networks, operating in unlicensed bands, are promising because they permit both private and public backends. Unfortunately, their target applications are situations where sporadic transmissions are tolerated. They could not fit scenarios in which high reliability and short round trip time are required. In this article, the LoRaWAN solution is considered for managing emergency and alarm communications. Reliability and timeliness limits have been overcome by jointly using a message replication scheme with variable payload length together with low-cost repeaters. Experiments have been carried out in both fixed and low-speed mobility scenarios (with an interfering traffic of 95 message/h, generated by regular LoRaWAN colocated network). Results, in the former case, show that the success probability of confirmed messages is 100%, the 99.6% of the available data are delivered to the backend, and the average delay decreases by 150 ms. When mobility is considered (e.g., for an automatic guided vehicle use case) results confirm significant improvements for both the transaction success ratio and the data extraction rate that significantly increase up to 95% and 87%, respectively. On the contrary, the overall average delay is not always reduced.

Low Power Wide Area Networks (LPWANs) are wireless technologies well accepted in the Internet of Things (IoT) scenarios because they operate in both public and private infrastructure using unlicensed frequency bands. Differently from other wireless standards, the LPWAN target applications are low-rate, sporadic-transmission, low-energy systems. Surely, fast response time and high reliable communication are out of the original LPWAN scope. In this work, a first investigation about the use LoRaWAN (one the most diffused LPWAN protocols) for notification of emergency messages across industrial plants is reported. The opportunity of using recently proposed low-cost repeaters, and the creation of a clever replication pattern of radio messages are the keys of the proposed approach. The results of the preliminary analytical feasibility assessment are presented, confirming the possibility to increase success ratio of notification and respective confirmation in case of emergencies.

Recently, designers of the home automation framework are looking to the Internet of Things (IoT) model to make it easier to deploy devices capable of gathering data from various plants. This situation is pushing a further evolution: from the conventional building automation, where the logic is determined by the installer or by the customer, to a cognitive system, capable of learning from the customers' preferences what the best plant configuration would be. The aim of this research work is to identify issues related to the implementation of cognitive solutions during the renovation process of buildings. The paper proposes a cognitive framework to help the operation and management phases of buildings, by means of the digitalization of the supply chain of the construction industry, from the single building aspect to the entire construction cycle. The paper presents the design of smart building elements with integrated capability to generate a massive amount of data for monitoring the energy and maintenance status of renovated buildings. The IoT paradigm has been used to link the physical word of building elements with the cognitive layer. The proposed approach has been applied and validated into a real test case.

The LoRaWAN technology, an example of low power wide area network, is considered a possible IoT-derived solution for realizing private cellular (single-hop) communications in the industrial domain. However, despite LoRaWAN promises long range and dense environments with many obstacles (as the industrial ones), it may suffer from coverage issue. Additionally, the inverse relationship between data rates and range may be unacceptable for many industrial applications. In this article, an innovative LoRaWAN range extender (based on an enhanced LoRaWAN node) is described, and its integration in the infrastructure of industrial Internet of Things (IIoT)-enabled industrial wireless networks is presented. A frame relay strategy is suggested, thus avoiding to tradeoff the highest data rates against an increased sensitivity. The feasibility of the solution is formally verified and the features of the realized proof-of-concept prototype, based on commercially available hardware, are discussed. The experimental results, obtained with a purposely designed test bench, show the effectiveness of the proposed approach. In particular, the range extender is transparent for legacy LoRaWAN networks as confirmed by correct relaying of uplink and downlink for different types of LoRaWAN message.

Smart Grids deployment is growing around the world. The expansion of the existing Smart Grid network infrastructure in order to connect new electrical substations (or end-users) may be impaired by difficult cable deployment. For this reason, recently, wireless communication links have also been used. This paper deals with the deployment, and the first characterization, of an IEEE 802.11ac connection between IEC 61850 electrical automation devices. Some configurations of IEEE 802.11ac have been tested and compared with usual cable connection. The use of GPS based instrumentation combined with IEEE 1588 clock synchronization allows reducing measurement uncertainty and producing meaningful results. For instance, the IEC 61850 Transfer Time between GOOSE (Generic Object Oriented Substation Event) publisher and subscriber over an IEEE 802.11ac wireless link, loaded with 80Mbit/s of traffic, has an average value of 5.4 ms and a maximum value of 10 ms.

Large industrial automation networks based on Real-Time Ethernet protocols may need efficient multicast management and filtering in order to control traffic load and to guarantee the desired quality of service. Very often industrial network are required to be highly available, implying the use of redundancy protocols, and thus, the use of dynamic (layer 2) multicast reconfiguration may be effective. This paper evaluates the application of standard IEEE Multiple MAC registration Protocol (MMRP) to industrial automation scenarios. Two main application fields are considered: large (and slow) process automation plants; and fast factory automation networks inside electric substations for measuring and protection. Following analytical and simulation approaches complete model of MMRP has been developed. Last, a new set of protocol parameters is proposed to maximize effectiveness of MMRP in industrial scenarios: a great network load reduction and a multicast reconfiguration time of 40 ms after a fault can be obtained in networks with complex topology.

Real-time networks for substations automation systems are based on ICT technologies and they may take great advantages from ultra recent network technological improvements. A careful evaluation of the performance enhancement is required. Due to cost and system complexity, such an analysis can be performed only using a dedicated simulation environment, but the currently available simulation libraries are not focused on lower layers (L1, PHY, and L2 MAC). The main objective of this work is to introduce the architecture of a modular network simulator, with suitable models of L1 and L2 Ethernet layers, for the simulation and co-simulation of substation automation Real-time Ethernet networks. The modular simulator includes interfaces for both co-simulation with FPGA-hardware board and real network, and co-simulation with automation application software (e.g. IEC61850 SCADA system, etc.).

This paper deals with the adoption of wireless communications in industrial automation. Most diffuse wireless systems require the deployment of a fixed infrastructure, with sufficient nodes acting as coordinators; this approach is typically applied also in automation. Conversely, a decentralized wireless solution is here proposed: it is based on a synchronous and connection-oriented protocol studied for vehicular communications. The protocol, called MS-Aloha, guarantees a multi-hop coordination with dynamic resource reservation, spatial slot re-use and hidden terminals prevention. The proposed solution has been modeled and simulated in order to quantitatively demonstrate how much its determinism and multi-hop coordination can be beneficial to the automation, in comparison to CSMA/CA. The simulated scenarios address the evaluation of the latency, delay variation, and delivery rate in critical conditions involving hidden terminals and close to congestion.

The paper describes the application of an improved Time Gateway for simplifying the integration of old IEC 61850 devices in new IEC 61850 Substation Automation System with IEEE 1588 PTP. Old devices typically retrieve time information with the well-known SNTP protocol which uses very different time representations and synchronization strategies with respect to PTP. Hence, the paper uses a transparent, full-software, Time Gateway for interfacing SNTP devices with a PTP synchronization domain, demonstrating its applicability by means of a prototype based on an FPGA. Experimental results show the Time Gateway improves the overall performance with respect to an SNTP-only system. Moreover, the experiments demonstrate that the synchronization accuracy is limited by the SNTP.

The paper presents a case study regarding a real PROFINET IO network for factory automation. The aim of the study is the evaluation of the time related parameter of a real network. A large factory automation plant has been chosen as testbed since PROFINET IO RT Class 1 and 2 (unsynchronized) are mainly used in those applications. The analyzed network has a high number of distributed IO, actuators and sensors; its topology is complex (star and ring); and it is fully operative (in-production). The considered implementation stresses the PROFINET IO communication as no laboratory setup can do, giving meaningful information about real operative conditions on short-term. The results of this case study can be used both to improve simulation models of devices and to verify critical situations in real plants.

Several types of industrial Real-Time Ethernet (RTE) networks could be present in the same plant. This work deals with the clock synchronization problems that arise when different RTE network infrastructures are interconnected. Specifically, this paper is focused on the exploitation of PROFINET IO Conformance Class C infrastructure for the interconnection of other industrial communication devices or measurement instruments that use IEEE1588 for clock synchronization. Actually, such devices (e.g., LXI instruments, EtherNet/IP devices, etc.) cannot be satisfactorily synchronized if directly connected to the PROFINET infrastructure, because of the large time errors (up to 100 μs). The solution proposed in this paper is an intelligent clock synchronization converter that has fewer limitations if compared with other systems, like boundary clocks. The basic idea is the creation of a “black-box” (a sort of remote bridging device) for the interconnection of IEEE1588 nodes through a PROFINET IO host plant, with zero-configuration on both systems. The proposed approach differs from boundary clock since its goal is to keep the PROFINET IO and the IEEE1588 synchronization domains separated, exploiting the possibility to tunnel the IEEE1588 time information through the PROFINET IO infrastructure with sufficient precision. In order to verify the practical feasibility of the proposed solution, LXI Class B instruments have been connected to the infrastructure of a real PROFINET IO network. The results show that the standard deviation of the synchronization accuracy is only 10 ns higher than the one measured in the case of a dedicated (separated) network for the LXI instruments.

In this paper a novel and simple CMOS integrated interface is presented. The circuit is suitable for typical gas sensor applications being able to reveal: a) high resistive values over a wide-range (more than five orders of magnitude, ranging from hundreds of kilohm up to tens of gigohm); b) relatively low value capacitances (few picofarad) and their variations. The proposed front-end utilizes, as active blocks, operational amplifiers that have been implemented, at transistor level, as suitable OTA showing low input voltage offset and relatively high slew-rate characteristics. With respect to the most topologies in the literature, the proposed interface, based on an oscillating architecture, is very simple and allows to obtain good performances all over a high dynamic range without any initial calibration. System sensitivity has been set to 0.1 ms/MOmega. Experimental measurements, performed on chip, fabricated in a standard and low-cost CMOS technology (AMS 0.35 mum), have shown a good linearity confirming the front-end validity in a large frequency range.

The paper deals with IEEE1588 PTP-based devices which are installed in industrial plants together with PROFINET IO Class C. In fact, devices with PTP for clock synchronization (e.g. LXI instruments, Ethernet/IP nodes etc.) exhibit noticeable time errors if directly connected to the PROFINET infrastructure. In the paper, possible architectures to overcome this limitation are evaluated (i.e boundary clock), then an intelligent clock synchronization converter is proposed. The core idea is to create a black-box that does not require configuration neither of the PTP-based nodes nor of the host plant. The proposed converter has been applied to a PROFINET IO network that hosts PTP-based devices. Preliminary results show that, if compared with a direct connection of PTP-based nodes, the converter worsens the synchronization accuracy of less than 10 ns.

This paper deals with the problem of coexistence of wireless sensor networks (WSNs) for industrial applications, proposing new approaches. In fact, if several WSNs operate in the same area, the reliability of the system rapidly decreases, especially if static radio channel assignment WSNs and frequency hopping WSNs are mixed. The proposed architecture is based on a collaborative approach that exploits synchronization capability of some WSNs to improve coexistence. In order to prove the feasibility of this approach, a simulation framework has been created and real prototypes have been evaluated by means of on-the-field measurements. Experimental results, in terms of number of coexisting WSNs and node battery life improvements, show a very good agreement with simulations.

Ethernet technology is widely used in real-time industrial automation. Thanks to real-time Ethernet (RTE) protocols, defined in IEC61784-2 standard, new top-performance automation solutions can be created. Such systems may have communication cycle time down to tens of mus and cycle jitter less than 1 mus, making network testing and debugging very critical. Existing network and protocol analyzers can perform detailed local analysis, but characterization of high-performance RTE systems requires measurement of transmission delays and these instruments cannot be adequately synchronized among them to realize a distributed measurement network. This paper introduces a new low-cost distributed measurement instrument to measure timing characteristics of RTE nodes (end-to-end delays, synchronization, etc.). The proposed instrument has multiple FPGA-based probes that allow for simultaneous/synchronized logging on different place of the target RTE network. A PC-based "monitor station" stores all the data, ready for further elaboration. Architecture details are discussed, a prototype has been realized, and some experimental results are presented. For instance, synchronization accuracy between probes is below 100 ns.

This paper discusses the use of distributed instruments for performance evaluation of real-time Ethernet (RTE) networks. A new instrument, composed of several logging probes connected in different points of a RTE target network, is characterized and compared with commercially available test equipments. The most important problem in performance evaluation is the timestamp assignment to network events; special attention has been paid in measuring synchronization uncertainty among probes. In fact, experimental results show a synchronization accuracy less than 150 ns on timestamp assignments among probes of the same instrument. In the last part of the paper, a sample application on a real network has been described, illustrating the use of the proposed instrument.

The PROFINET architecture can provide real-time, high-performance, isochronous communication regardless the presence of other real-time data exchange and TCP/IP traffic for a considerable portion of network bandwidth. In this work some experimental tests have been executed in order to evaluate timing performance of a PROFINET ASIC (ERTEC 400 chip) and its related development kits. Results shows that communication isochrony has been ensured with a jitter of about 100 ns despite TCP traffic (70% of bandwidth) and presence of PROFINET IO RTjClass 1 nodes. On the contrary, some improvements are still needed as regard features of the software stack and of the interface with the application layerl. The highlighted problems will be probably fixed in the next firmware releases planned by manufacturer.

This paper introduces a new Ethernet based communication system, called GDNET, that allows isochronous I/O management tailored for high-performance plastic machinery. In the typical application (four slaves) GDNET allows 6000 I/O points to be scanned in 200 mus. GDNET is independent from hardware and software choices regarding the PC-based master (processor, network interface card, switches, RTOS...), avoiding the need of a jitter-free clock source, still keeping remote input output synchronization in the order of microseconds. Experimental results show that delay between an event (threshold crossing of an analog input) and the corresponding logic output is 800 mus with a standard deviation below 3 mus. Effectiveness of the proposed system is proved by more than 1400 installations.

This paper deals with real-time Ethernet networks based on PROFINET IO Class 1. Generally, industrial automation has a cyclical behavior; jitter in the application cycle depends on many factors and has direct consequences on production quality. In this work, in order to simplify application jitter estimation of complex systems, measurement techniques are introduced and some initial experiments on real devices are presented. Particularly, methods to experimentally estimate the cycle time of bus, IO-Controller and IO-Devices are proposed. Last, some analytical relations have been obtained: preliminary results show an estimation error less than 5%.