#ISO 13849 Safety of Machinery- Safety-related parts of control systems.

Type B-1 standard. Safety-related parts of control systems (SRP/CS) are parts of the control system assigned to provide safety functions. The Ability of SRP/CS to provide safety functions is allocated one of five performance levels (PL). They are B, 1, 2, 3 and 4. This standard provides a methodology for assessing the PL of the design or performance of a control circuit.