Phoenix Contact has published a free White Paper, Functional safety via wireless Ethernet (1.8MB PDF), written by Jürgen Weczerek. This will be essential reading for anyone considering using wireless technology for functional safety on machines or processes.
Wireless connectivity is gaining in popularity for automation tasks, whether as an alternative to sliprings or simply for ease of installation. However, many machine builders and system integrators have been reluctant to implement wireless safety-related systems. Phoenix Contact's new white paper considers both WLAN 802.11 and Bluetooth protocols, and also discusses wireless transmission of safety data via Profinet, ProfiSafe and Phoenix Contact's SafetyBridge technology.
The white paper explains how data transmission works for safety-related data, and the essential requirement for a robust and reliable wireless transmission method. In addition, there is a discussion of data security and its increased importance for wireless communications in order to prevent inadvertent or malicious interference with the safety system.
A substantial section in the white paper deals with the topic of system availability. This covers planning and installation, as well as antenna selection, and explains how Bluetooth's adaptive frequency hopping (AFH) and how Bluetooth and WLAN can be implemented reliably alongside each other, with Bluetooth utilising the gaps between the WLAN channels. The coexistence of Bluetooth and WLAN is also discussed with respect to Profinet and ProfiSafe.
Towards the end of the white paper the Phoenix Contact SafetyBridge technology is presented. In particular, the white paper highlights the fact that SafetyBridge works independently from the respective network and does not need a separate safety controller. Safety-related data signals up to PL e or SIL 3 can be transmitted wirelessly, so cabling can effectively be replaced by SafetyBridge units without altering the safety characteristics of the safety-related control system.