A lock device for sliding gates has a harpoon-type bolt element whose head enters a cavity of a keeper from a shaped hole, and is pushed inside a sleeve by a roto-translation that is controlled by a cam and tappet coupling until the system is locked Reverse motion is prevented by engagement between the anchor of a solenoid and an elongated cavity on the surface of the bolt shaft, however allowing the bolt to tolerate axial displacements from thermal changes or settlements. An unlock control logic allows release of the engagement via a European profile lock cylinder, a mechanical control remotely operated through a Bowden wire, or an electrically controlled solenoid. The control logic ensures the system operation follows the correct direction of motion of a cyclic state machine, to provide proper synchronization with the operation of the gate automation.