Couplers & I/O modules: Item no. 750-661/000-003 Fail-safe 4-channel digital input; 24 VDC; PROFIsafe V2.0 iPar Item no. 750-661/000-003 Fail-safe 4-channel digital input Discontinued Downloads as zip Download Compare Find distributors Configure Item no. 750-661/000-003 Fail-safe 4-channel digital input Discontinued Downloads as zip Download Compare Find distributors Configure