Siemens SIMATIC CPU 410 System Manual page 387

Redundant I/O
Table A-1 MTBF factors of the redundant I/O
Module
Digital input modules, distributed
DI 24xDC24V
DI 8xNAMUR [EEx ib]
DI16xDC24V, Alarm
Analog input modules, distributed
AI 6x13Bit
AI8x12Bit
Digital output modules, distributed
DO 10xDC24V/2A
DO8xDC24V/2A
DO32xDC24V/0.5A
Summary
Several thousand redundant automation systems are in use in different configurations in
manufacturing and process automation. To calculate the MTBF, we assumed an average
configuration.
Based on experience in the field, an assumption of MTBF of 3000 years is 95% reliable.
The system MTBF value calculated is about 230 years for a system configuration with
redundant CPU 410-5H.
CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC
Characteristic values of redundant automation systems
A.2 Comparison of MTBF for selected configurations
MLFB
6ES7 326–1BK02–0AB0
6ES7 326-1RF00-0AB0
6ES7 321–7BH01–0AB0
6ES7 336-1HE00-0AB0
6ES7 331-7KF02-0AB0
6ES7 326–2BF01–0AB0
6ES7 322-1BF01-0AA0
6ES7 322–1BL00–0AA0
MTBF factor
See following
table
MTBF factor
CCF = 1%
approx. 5
approx. 5
approx. 4
approx. 5
approx. 5
approx. 5
approx. 3
approx. 3
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