Siemens S7-300 - Page 97

Digital modules
8.3 SM 326; DI 24 x DC 24V
Fail-safe signal modules
Installation and Operating Manual, 01/2010, A5E00085586-10
97
Wiring scheme for application 6 with two-channel connection of two redundant two-channel sensors
Two two-channel, redundant sensors are required per process signal. One sensor is
connected via two channels to each of two
opposite inputs of the digital module for each
module (1oo2 evaluation). The sensors can also be connected to an external sensor supply.
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9V
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9V
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9V
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OHIWFKDQQHOVWR
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Figure 8-21 Wiring scheme of the SM 326; DI 24 x DC 24V for application 6 – two two-channel,
redundant sensors two-channel connection
WARNING
To achieve SIL3/Cat.4/PLe using this wiring, you must use a suitably qualified sensor.