Siemens SINUMERIK Series Function Manual page 188

Standards and specifications
9.1 General
In this case, it is necessary to use specially qualified technology that fulfills the requirements
described in the associated Standards. The requirements to achieve functional safety are
based on the following basic goals:
● Avoiding systematic faults
● Controlling systematic faults
● Controlling random faults or failures
The level of the functional safety achieved is expressed using different terms in the standards.
In EN 61508, EN 62061, EN 61800-5-2: "Safety Integrity Level" (SIL) and EN ISO 13849-1
"Performance Level" (PL).
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Function Manual, 10/2015, 6FC5397-3EP40-5BA3
Safety Integrated