Rockwell Automation 1794 FLEX I/O System with ControlLogix for SIL2 - Manual (Page 12)

Publication 1794-RM001G-EN-P - December 2011
1-8 SIL Policy
Hardware Designs and
Firmware Functions Diagnostic hardware designs and firmware functions designed into the
ControlLogix/FLEX I/O platform allow it to achieve at least SIL2
certification in a single-controller configuration. These diagnostic features are
incorporated into specific FLEX I/O components, such as the:
• adapter
• power supply
• I/O modules
• terminal base units
and are covered in subsequent sections. The ControlLogix/FLEX I/O
platform’s designs, features and characteristics make it one of the most
intelligent platforms.
Difference Between PFD
and PFH Table 1.2 and Table 1.3 present values of the PFDs and PFHs for the specific
FLEX I/O products evaluated by TUV.
FLEX I/O uses the same PFD and PFH assumptions as stated in publication
1756-RM001 .
Table 1.2 FLEX I/O Product Probability of Failure on Demand (PFD) Calculations (T
1
= 1
yr
)
Catalog Number Description Mean Time
Between Failure
(MTBF)
(1)
λ
(3)
Calculated PFD
1oo2 architecture
1794-ACN15 ControlNet Single Media Adapter 8,223,684 1.22E-07 2.15E-06
1794-ACNR15 ControlNet Redundant Media Adapter 8,223,684 1.22E-07 2.15E-06
1794-AENT 10/100Mb Ethernet Communication Adapter 691,134 1.45E-06 2.76E-05
1794-AENTR 10/100Mb Ethernet Redundant Communication Adapter 1,268,070 7.89E-07 1.45E-05
1794-IB10XOB6 10 Input/6 Output Module 4,943,442 2.02E-07 3.60E-06
1794-IB16 16 Sink Input Module 4,105,090 2.44E-07 4.34E-06
1794-IE8 Analog Input Module 37,952,679 2.63E-08 4.64E-07
1794-IF2XOF2I Isolated Analog Input/Output Module 25,296,960 3.95E-08 6.97E-07
1794-IF4I Isolated Analog Input Module 11,746,343 8.51E-08 1.50E-06
1794-IJ2 Frequency Counter Module 2,418,321 4.14E-07 7.45E-06
1794-IP4 Pulse Counter Module 2,375,360 4.21E-07 7.58E-06
1794-IR8 RTD Input Module 6,191,655 1.62E-07 2.87E-06
1794-IRT8 TC/RTD/mV Input Module 1,182,438 8.46E-07 1.56E-05
1794-IT8 Thermocouple Input Module 1,564,324 6.39E-07 1.17E-05
1794-OB16 16 Source Output Module 1,883,594 5.31E-07 9.62E-06
1794-OB16P Protected Output Module 2,135,280 4.68E-07 8.46E-06