Siemens SIMATIC S7-400H - Digital Output Module Connected Through;Without Diodes; Fault-Tolerant Digital Output Module in a 1-Of-2 Configuration; Redundant Digital Output Modules

Using I/O on the S7-400H
7-21
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
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
Wiring without external diodes
Figure 7-9 Fault-tolerant digital output module in a 1-of-2 configuration
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 Digital output module connected through/without diodes
Modules
with diodes without diodes
6ES7 422-7BL00-0AB0 X –
6ES7 422-1FH00-0AA0 – X
6ES7 326-2BF00-0AB0 X X
6ES7 322-1BL00-0AA0 X –
6ES7 322-1BF01-0AA0 X –
6ES7 322-8BF00-0AB0 X X
6ES7 322-1FF01-0AA0 – X
6ES7 322-8BH00-0AB0 X –
6ES7 322-5SD00-0AB0 X –