Computer communication in modern factories can be considered complex due to its heterogeneity, various demands of timing, large datasets and countless timeseries, as well as needs for context oriented data handling. The paths, content and time requirements of the data flow may vary due to the flexibility of production, current settings, location on the shop floor, and the temporary nature of some Machine-To-Machine dialogues. Sometimes, because of mutable but indispensable interoperability of various subsystems, the application relationships between nodes must be established as transient, on-demand only, and without wired infrastructure. In this case, ad-hoc wireless networks are required, and awareness of radio link reliability is essential due to inevitable disturbances and general real-time and dependability requirements. Against this background, an analysis of a temporary and short distance wireless channel between two nodes is presented in the paper. It was carried out briefly theoretically and thoroughly empirically based on delay measurement on the link layer of IEEE802.15.4, Bluetooth 5, and WiFi 4. The results allow to determine the scope of applicability of this type of pseudo-deterministic low level connection and depict the guidelines for communication design.

Modern industrial systems require more and more flexibility and mobility; furthermore the quantity of data generated by them is great. In some cases, classical wired networks are not feasible due to the type of device itself (e.g., AGV) or its location. In such cases wireless communication is the only solution. The then, the choice of appropriate communication protocol, especially in an industrial system, is crucial. The paper presents an approach of using a wireless connection in EtherCAT network, which in principle is a wired solution. Therefore, for wireless communication upper layer protocol has to be implemented. Here, Software Defined Networks SDN technology is used. SDN allows for dynamic and programmable infrastructure management and monitoring of network traffic. The proposed solution was compared in terms of performance to a standard wired connection. To do this research and confirm the theoretical assumptions industrial devices like PLC controllers, remote IO stations and servo drives were used. The paper shows limitations resulting from this type of communication and the possibility to reduce their significance.