The TM5/TM7 Safety I/O modules are a Safety-Related System certified according to IEC 61508 by TÜV Nord.
The IEC 61508 is a technical standard concerning the functional safety of electrical, electronic or programmable electronic safety-related systems.
A safety-related system is a system that is required to perform one or more specific functions to ensure that risks are kept at or below an acceptable level. Such functions are defined as safety functions.
A system is defined “functionally safe” when random, systematic, and common cause equipment or machine failures do not lead to malfunctioning of the system and do not result in injury or death of humans, spills to the environment, and loss of equipment and production.
Safety-related functions are executed to achieve and maintain the defined safe state of a system. The IEC 61508 specifies four levels of safety performance for a safety-related function. These are called Safety Integrity Levels (SIL), ranging from 1 (the lowest) to 4 (the highest). The TM5/TM7 Safety I/O modules are certified for use in SIL 3 applications in which the de-energized state is the defined safe state.