FIELD: protective and signalling means, supervision of premises. SUBSTANCE: body of device houses cylinder with duct and key hole. Springy plates attached with one ends to body and resting against cylinder with other ends are placed into clearance between body and cylinder. Code member (plate) provided with code holes made at different heights from surface of cylinder is attached to cylinder in parallel to duct. Angular cut thanks to which code member can turn about its axis that falls outside the limits of body is made in cylinder along duct. Laminated key has code protrusions. Essence of method of warning lies in that with generation of alarm signal body remains immobile and code member turns under action of butts of spring-loaded plate(s) to side opposite to side of turn of cylinder. Fact of turn of axis is primary signal of penetration attempt into protected room. EFFECT: simplified design and enhanced reliability of operation of device. 4 cl, 4 dwg
