Redundant Digital Output Modules; Digital Output Module Connected Through/Without Diodes; Fault-Tolerant Digital Output Module In A 1-Of-2 Configuration - Siemens SIMATIC S7-400H Manual

Redundant digital output modules

The fault-tolerant control of an actuator can be achieved by connecting two outputs
of two digital output modules or fail-safe digital output modules in parallel
(1-out-of-2 configuration)
Wiring with external diodes
Figure 7-9
The digital output module have to have a common 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".
Wiring with external diodes <–> without external diodes
The table below shows which of the digital output modules you interconnect by
means of external diodes (cf. diagram 7-9) for operation in redundant mode:
Table 7-2
6ES7 422-7BL00-0AB0
6ES7 422-1FH00-0AA0
6ES7 326-2BF00-0AB0
6ES7 322-1BL00-0AA0
6ES7 322-1BF01-0AA0
6ES7 322-8BF00-0AB0
6ES7 322-1FF01-0AA0
6ES7 322-8BH00-0AB0
6ES7 322-5SD00-0AB0
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07

Fault-tolerant digital output module in a 1-of-2 configuration

Digital output module connected through/without diodes

Modules
Using I/O on the S7-400H
Wiring without external diodes
with diodes
X
–
X
X
X
X
–
X
X
without diodes
–
X
X
–
–
X
X
–
–
7-21