1. Main Characteristics: 1. Self-checking function When the device has the malfunctions happen or suffers from sudden power off, it doesn't send the mistaken signal to equipment protected. 2. Anti-interference Not affected by periphery lights such as the electromagnetism signal, strobe, welding arc etc. 3. Self-locking function When the light curtain beam( one or more) is interrupted, controller sends output signal to brake the press's movement at once and the movement can't restart until press the "reset" button, meanwhile light passing as well. 4. High-reliability, Three safety reply output, 3N/O or 2N/O,1N/C output; respond time