ControlLogix 5590 SIL Requirements
A risk assessment determines whether a safety function requires SIL 2 or SIL 3.
For SIL 2 and SIL 3 requirements in high availability systems, see the ControlLogix 5590 High Availability Systems User Manual, publication 1756-UM901.
ATTENTION:
The safety signature is required for the controller to operate at a SIL 2 or SIL 3 rating. Controller operation without a safety signature is only suitable during development.
IMPORTANT:
High-demand SIL 2 applications that follow the IEC 61511 standard require a Hardware Fault Tolerance of 1 and must use the guidance for SIL 3 requirements throughout this documentation.
High-demand SIL 2 applications that follow the IEC 62061 standard require a Hardware Fault Tolerance of 0 and must use the guidance for SIL 2 requirements throughout this documentation.
SIL 2 Requirements
The following applies to SIL 2 safety functions:
- A safety-enabledControlLogix®5590 controller requires only the primary controller.
SIL 3 Requirements
The following applies to SIL 3 safety functions:
- A safety-enabledControlLogix®5590 controller requires both the primary controller and the safety partner.
IMPORTANT:
The safety task can contain a number of safety functions. For a particular function to be SIL 3, the entire chain of devices and programming from the sensor to the actuator must be SIL 3. Be careful that you do not use a SIL 2 input signal for a safety function that requires SIL 3.
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