Siemens S5-135U/155U appendix Connecting Non-Floating or Floating Modules, Cpu

Installation Guidelines

3.4.3Connecting Non-Floating or Floating Modules

Shown in the following sections are the specical features when installing non-floating and floating modules.

Installation with In an installation with non-floating modules, the reference potentials of the

Non-Floatingcontrol circuit (0 Vint) and load circuits (0 Vext) are electrically connected.

Modules

The reference potential of the control circuit (0 Vint) is given by the PE or protective conductor terminal and must be connected to the reference potential of the load circuit via an externally laid conductor.

Shown in the following figure is a simplified installation with non-floating modules. The arrangement is independent of the grounding concept. The connections for grounding are therefore not drawn.

Uint

Data 0 V

PS CPU DI DQ

1L+
1L±
PE
Control Power	External Connection for a
Supply	Standard Reference Potential
2L+
2L±
DC 24 V Load Power Supply		À

Figure 3-11 Simplified Representation of an Installation with Non-Floating Modules

The voltage drop on line À must not exceed 1 V. Otherwise there will be a shift in reference potentials resulting in module malfunctions.

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