Hardware Designs And Firmware Functions; Difference Between Pfd And Pfh; Aentr 10/100Mb Ethernet Redundant Communication Adapter 1 - Allen-Bradley 1794 Reference Manual

1-8 SIL Policy
Hardware Designs and
Firmware Functions
Difference Between PFD
and PFH
Table 1.2 FLEX I/O Product Probability of Failure on Demand (PFD) Calculations (T
Catalog Number Description
1794-ACN15 ControlNet Single Media Adapter
1794-ACNR15 ControlNet Redundant Media Adapter
1794-AENT 10/100Mb Ethernet Communication Adapter
1794-AENTR 10/100Mb Ethernet Redundant Communication Adapter
1794-IB10XOB6 10 Input/6 Output Module
1794-IB16 16 Sink Input Module
1794-IE8 Analog Input Module
1794-IF2XOF2I Isolated Analog Input/Output Module
1794-IF4I Isolated Analog Input Module
1794-IJ2 Frequency Counter Module
1794-IP4 Pulse Counter Module
1794-IR8 RTD Input Module
1794-IRT8 TC/RTD/mV Input Module
1794-IT8 Thermocouple Input Module
1794-OB16 16 Source Output Module
1794-OB16P Protected Output Module
Publication 1794-RM001G-EN-P - December 2011
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.
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.
= 1 )
1 yr
(3)
Mean Time λ
Between Failure
(1)
(MTBF)
8,223,684 1.22E-07
8,223,684 1.22E-07
691,134 1.45E-06
1,268,070 7.89E-07
4,943,442 2.02E-07
4,105,090 2.44E-07
37,952,679 2.63E-08
25,296,960 3.95E-08
11,746,343 8.51E-08
2,418,321 4.14E-07
2,375,360 4.21E-07
6,191,655 1.62E-07
1,182,438 8.46E-07
1,564,324 6.39E-07
1,883,594 5.31E-07
2,135,280 4.68E-07
Calculated PFD
1oo2 architecture
2.15E-06
2.15E-06
2.76E-05
1.45E-05
3.60E-06
4.34E-06
4.64E-07
6.97E-07
1.50E-06
7.45E-06
7.58E-06
2.87E-06
1.56E-05
1.17E-05
9.62E-06
8.46E-06