Redundant Analog Input Modules With Redundant Sensors; Fault-Tolerant Analog Input Modules In A 1-Out-Of-2 Configuration - Siemens SIMATIC S7-400H Manual

Using I/O on the S7-400H
Note
This circuit supports only 2-wire measurement transducers with external 24-V
power supply or 4-wire measurement transducers. For this circuit you can not use
the integrated measurement transducer supply voltage, because its output voltage
is only 13V and in worst case it would thus only supply 5 V to the transducer.

Redundant analog input modules with redundant sensors

Analog input modules in a 1-out-of-2 configuration are preferred for double
redundant sensors:
Figure 7-11
The use of redundant sensors increases their availability.
Discrepancy analysis also detects external errors – except for the failure of a
non-redundant on-load voltage supply.
Connection examples are available in Appendix F and in the SIMATIC FAQs at
http://www.siemens.com/automation/service&support under the
keyword "Redundant I/O".
The general information in the introductory section applies.
Additional marginal conditions for various modules
AO 4x15bit Ex
Please note the relevant maximum current and voltage specifications for the
operation of modules in Ex applications.
7-30
Analog input
module
Fault-tolerant analog input modules in a 1-out-of-2 configuration with two
sensors
6ES7 332-5RD00-0AB0
Analog input
module
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07