LOW CURRENT BINARY INPUT SUBSYSTEM

摘要

Disclosed is a low current binary input subsystem (12) for providing a binary input signal (IN) to a data acquisition system (14). The binary input subsystem (12) monitors the open/close state of a field contact (10) and provides galvanic isolation of noisy field contacts (10), high noise immunity, a steady state current of approximately 1.2 milliamps resulting in power dissipation of approximately 0.25 watts for a 125 VDC input, and a momentary high current pulse of approximately 150 milliamps for a duration of approximately 4 milliseconds during field contact closure to aid in cleaning of oxides from the field contact (10).