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S7-300 Automation System, Hardware and Installation: CPU 31xC and CPU 31x
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Please note the following points if you wish to arrange your modules on multiple
racks:
•
The interface module always uses slot 3 (slot 1: power supply; slot 2: CPU, slot
3: interface module)
•
It is always on the left before the first signal module.
•
No more than 8 modules (SM, FM, CP) are permitted per rack.
•
The number of modules (SM, FM, CP) is limited by the permitted current load
on the S7-300 backplane bus. The total power consumption must not exceed
1.2 A per row.
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The power consumption of the individual modules is given in the
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Special shielding and grounding measures are not required if you interconnect the
CU and EM using suitable interface modules (Send IM and Receive IM).
However, you must ensure that
•
all racks are interconnected with low impedance,
•
the racks of a grounded assembly are grounded in a star pattern,
•
the contact springs on the racks are clean and not bent, thus ensuring that
interference currents are dissipated.
