Siemens S7-300 - 5.3 Replacing Fail-Safe Signal Modules

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S7-300 Automation System, Hardware and Installation: CPU 312IFM - 318-2 DP
5-20 A5E00203919-01
The diagram illustrates an S7-300 configuration with grounded reference potential
(implemented with a jumper)
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1
3
4
2
Figure 5-7 S7-300 configuration with grounded reference potential (CPU 313 – 318-2 DP)
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1 The removable jumper
2 The grounding bus cable
3 The reference potential of the CPU interconnection
4 Rail
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If you wish to install an S7-300 with grounded reference potential, you must NOT
remove the jumper from the CPU.
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If you install an S7-300 with ungrounded reference potential, any interference
currents that occur are dissipated via an RC system to the ground conductor/local
ground integrated into the CPU.
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Floating potential installation of an S7-300 with CPU 312 IFM or CPU 31xC is not
possible.