System Configurations With Distributed I/Os - Siemens SIMATIC S7-400H System Manual

Characteristic values of redundant automation systems
A.2 Comparison of MTBF for selected configurations
A.2.2

System configurations with distributed I/Os

The system with two fault-tolerant CPUs 417-5H and one-sided I/Os described below is
taken as a basis for calculating a reference factor which specifies the multiple of the
availability of the other systems with distributed I/Os compared with the base line.
You can find the order numbers of the IMs in chapter Using single-channel, one-sided I/Os
(Page 171).
Redundant CPUs with single-channel, one-sided or switched I/Os
One-sided distributed I/Os
Switched distributed I/O, PROFIBUS DP, CCF = 2 %
442
Base line
1
Factor
approx. 15
System Manual, 03/2012, A5E00267695-11
S7-400H