Surveillance is monitoring of behavior, activities, or other changing information. Nowadays machines in the area of development and research as well as in a production environment getting more and more complex and expensive. Failures caused by improper use or by defect parts can cause a lot of damage. To prevent or at least to attenuate effects of such failures a surveillance unit is needed. This book analyzes requirements for surveillance units for safety critical machines. To demonstrate the concept the general approach will be specialized in a case study. To support the design phase in the case study, the system is analyzed with respect to Fault Tree Analysis (FTA) and Failure Mode and Effects Analysis (FMEA).