Allen-Bradley controllogix 1756-L55M12, User Manual

Page: 118 / 142

Publication 1756-UM001G-EN-P - January 2007
118 SIL 2 Certification
SIL 2 Application
In obtaining SIL 2 certification for a ControlLogix system, Rockwell
Automation did not need to create a special line of products to meet
stringent SIL 2 requirements. Sophisticated diagnostics and high levels
of reliability are standard in ControlLogix processors, I/O modules,
and communication products. It is that same standard design that
readily provides the reliability needed to achieve SIL 2 certification.
A typical ControlLogix SIL loop includes:
•
the overall safety loop.
•
the ControlLogix portion of the safety loop.
•
how other devices (for example, HMI) connect to the loop,
while operating outside the loop.
SIL 2 Application Overview
E
N
B
T
C
N
B
C
N
B
C
N
B
Programming Software
For SIL applications, a programming
terminal is not normally connected.
HMI
For Diagnostics and Visualization (read-only
access to controllers in the safety loop)
Plant-wide Ethernet/Serial Network
SIL2-certified ControlLogix Components Portion of the Overall Safety Loop
ControlNet Network
ControlNet Network
To Nonsafety-related Systems Outside the
ControlLogix Portion of the SIL2-certified Loop
Sensor Actuator
To Other
Safety-
related
ControlLogix
Remote I/O
Chassis