Digital modules
8.4 SM 326; DI 8 x NAMUR
Fail-safe signal modules
Installation and Operating Manual, 01/2010, A5E00085586-10
119
8.4.7
Application 6: Safety mode SIL3/Cat.4/PLe with high availability (in S7 F/FH
Systems only)
Introduction
Below are the wiring scheme and the parameter assignment of SM 326; DI 8 x NAMUR for
application 6: Safety Mode SIL3/Cat.4/PLe with high availability.
Diagnostic messages, possible causes of the problem and their corrective measures are
found in tables in the chapter "Diagnostic Messages for SM 326; DI 8 x NAMUR
(Page 121)".
Wiring scheme of application 6
Four single-channel, redundant sensors are connected via 2 channels to the two digital
modules for each process signal (1oo2 evaluation). The contacts of each sensor are routed
to two
opposing inputs of the same digital module. The sensor supply Vs is made available
from the respective digital module. The left channels of the module return the user signals,
that is, these signals are available in the I/O area of inputs at the F-CPU if no errors are
detected.
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Figure 8-31 Wiring scheme of the SM 326; DI 8 x NAMUR for application 6
WARNING
To achieve SIL3/Cat.4/PLe using this wiring, you must use a suitably qualified sensor.