Programmable controller with fiber optic input/output module

Abstract From the Canadian patent

A fiber optic communication system especially adapted for use with a programmable industrial controller includes a mechanism for evaluating the quality of the fiber optic link. The system includes a transmitter for sending a different unique character over the fiber optic cable at a plurality of light intensities. A receiver is coupled to the fiber optic cable for receiving the characters from the transmitter. The receiver determines whether information was received at each of the plurality of light intensities by determining which of the unique characters were received. In response to the determination of the light intensities that were received an evaluation of the quality of the fiber …