The FS-V31 is a digital, single-control fiber optic sensor designed for industrial applications, featuring NPN output and selectable Light-ON/Dark-ON operation. It operates on a 12-24 VDC input and has a low power consumption of 0. This manual provides essential instructions for the safe and effective use of the Keyence FS-V31 Fiber Optic Sensor. 1 ms to 9,999 ms, Maximum error against the setting value: ±10% max. NPN open-collector 24 V, 100 mA max. (when the. Current Value (4-digit red LED indicator) illuminated together. (when the. Introducing the FALCON IV, our latest upgrade in a revolutionary line of custom CPU's designed by KEYENCE specifically for our fiber optic sensors.