Fail-Safe Modules
7.3 PM-E F pp DC24V PROFIsafe power module
ET 200S Distributed I/O System - Fail-Safe Modules
Installation and Operating Manual, 08/2008, A5E00103686-07
85
Safety-Related Shutdown of Standard Output Modules
Refer to the Internet
(
http://support.automation.siemens.com/WW/view/en/12461959/133300) for a list of all the
standard ET 200S modules.
WARNING
Safety-related activation of standard DO module outputs is not possible. Only safety-related
shutdown is possible. The following issues must therefore be taken into consideration:
In the worst case you must consider all possible faults of the standard DO modules and the
programs controlling them for which the faults cannot be found directly. For example, the
PM-E F pp DC24V PROFIsafedoes not detect external short-circuits to L+ at the standard
DO module outputs.
All faults developing at the standard DO modules influence the process via final controlling
elements.
The process status must be made known to the F-CPU by way of sensors and a suitable
safety program.
The safety program must react in a safety-related and logically suitable fashion to
unwanted or potentially dangerous states in the process via the PM-E F pp DC24V
PROFIsafe and fail-safe output modules.
If you want to avoid the problems described above completely, we recommend that you use
P/M switching fail-safe electronic modules 4 F-DO DC24V/2A PROFIsafe with standard
ET 200S power modules instead of standard DO modules.
Properties of safety-related shutdown of standard DO modules with the PM-E F pp DC24V
PROFIsafe:
This cost-effective solution allows the full and simultaneous shutdown of all outputs involved
when a fault is detected in the process or on the PM-E F pp DC24V PROFIsafe.
Property of the individual shutdown of F-modules with fail-safe outputs:
The scope of shutdown is kept to a minimum when a fault is detected. It is also possible to
react to critical process states staggered over time, or to perform safety-related shutdown of
individual outputs. Compared to the safety-related shutdown by the PM-E F pp DC24V
PROFIsafe, this solution costs more.
See also
Assigning Modules of an ET 200S (Page 22)
Properties of the 4 F-DO DC24V/2A PROFIsafe digital electronic module (Page 163)
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