Fiber-optic interface system

摘要

A fiber-optic data-link used to interface a remote process variable sensor/transmitter to a local process control system includes a local light source module and a remote interface module interconnected by one or more optical fibers. Energy for operating the remote interface module and its associated process variable sensor/transmitter is provided by light energy transmitted from the local site to the remote site and converted at the remote site to an electrical signal. The local light source module and the remote interface module each may include a microcontroller. The controllers not only control the flow of status messages in either analog or digital or analog and digital form simultaneously from the remote site to the local site, but also insure the integrity of the system and minimizes the amount of optical power delivered to the remote site to that which is required to electrically power the remote interface module and the process variable sensor/transmitter, thus extending the useful life of the light source. The system is also arranged to check the integrity of the optical fibers to ensure that the light intensity is always below a minimum eye-safe value whenever the optical fiber is not correctly connected between the local light source module and the remote interface module.