Unlike the copper cable such as Cat 5, the fiber cable works very well in noisy environments. The other major advantage is less resistant in the signals traveling. The data can be transmitted to much further distances, up to 80 km, as opposed to the transmission on copper cables.
Serial to Fiber
Due to the easiness of setup and low cost, serial devices are used around the world of industrial systems. If greater distances are required, RS-485 increases the distance to 400 feet (or 1200 meters). However, the longer the copper cable, the more data corruption due to the electromagnetic (EMI) and radio frequency (RFI) interference.
Profibus to Fiber
Profibus is widely used in the DCS (Distributed Control Systems) which the system controllers are connected by networks for communication, control, and monitoring. Following is the diagram where the Profibus to Fiber can be used in the DCS.