Fiber optic lines are capable of bridging more than ten times the distance provided by copper cables, enabling users to transfer signals with the same bandwidth from Profibus DP field devices via distances of 2 km or more. Intrinsically safe ISpac 9186 type isolating repeaters even allow for communication between hazardous and safe areas. If required, the isolating repeaters can also be used to implement ring structures, ensuring high availability through the redundant route. Problems such as insufficient potential equalization, which can occur in Profibus cables with screen grounding, are ruled out on principle. Moreover, the light waves are not affected by electromagnetic interference from devices within and outside of the network. The only restrictions users face are installation requirements and, if required, the necessary explosion protection against light as an ignition source. The protection type “optical intrinsic safety” is particularly suited for that purpose – it not only ensures a safe limitation of optical energy per unit area, but also allows for particularly easy installation. ISpac 9186 type isolating repeaters feature Ex i and Ex op is protected data transmission interfaces. Therefore, the electric RS 485 plug and the fiber optic connection can be connected and disconnected at any time under load. Additionally, the easy-to-use isolating repeaters feature a unique diagnosis function which constantly analyzes the level of the received optical signal, displaying it via an LED bar at the unit's front side. If the receive level reaches a critical area, the isolating repeater additionally reports that status vial a potential-free contact.