Safety relays are devices which initiate all safety functions. In the past, relays were used to control the machinery during the start of the era of control technologies. Based on those device and their various combinations, safety relays were manufactured and the first safety relay was introduced by Pilz, a German automation company. In case of accidents or hazards, safety relays start functioning in order to control the damage by reducing the standing risks to a tolerable level. There are many safety functions that the safety relays carry out. Few of the safety relays that carry out the safety functions include safety gates, pushbuttons for emergency stopping, light beam devices, time delay, two hand controls and pressure sensitive mats. One safety relay is responsible to monitor and control one specific function, but when coupled with several other safety relays, the combination can monitor the operations and processes of the entire plant. The difference between several safety rela...