Evaluation of Communication Delay in IOT Applications Based on OPCUA

摘要

The grow of Industry 4.0 is pushing the deployment of the Industrial Internet of Things (IIoT) allowing many (all) industrial devices to be connected to the Internet for data sharing. Based on the enormous amount of data stored in the Cloud, new analysis algorithms can be run and the extracted information can be sold as “service”. Even if today the Industry 4.0 applications have still a slow reaction time, it is clear that “short latency services” may have competitive advantage in the market. For this reason, this paper is focused on the evaluation of the communication delay due to the transfer of data from the source (i.e. the production line) to the Cloud and the way back. The reference architecture considered in this paper is based on: the well accepted OPC UA (Open Platform Communications Unified Architecture) access method for retrieving data directly from the device inside the production line; and a classic gateway approach for sending data in real (commercial) Cloud platforms. In this paper a test methodology is proposed and a use case is presented to show its feasibility. The experimental outcomes demonstrate that, by means of the proposed methodology, flexible solutions based on OPC UA combined with industrial grade IoT gateways can be easily evaluated. From the perspective of the considered use case, the average delay due to communication from the production line (in details: from a Siemens S7 1500 controller) to the Cloud (IBM Bluemix platform) is less than 300 ms with a standard deviation of about 70 ms over two weeks observation time.