Siemens S7-400 installation manual Electrical Supply, Communication Bus C Bus

Installing the S7-400

Electrical Supply

The modules inserted in the rack are supplied with the required operating voltages (5 V for logic, 24 V for interfaces) via the backplane bus and base connector, by the power supply module fitted in the slot on the extreme left in the rack.

For local connections, ERs can also be supplied with power via the IM 460-1 / IM 461-1 interface modules.

5 A may flow through each of the two interfaces of a send IM 460-1, meaning each ER in a local connection can be supplied with up to 5 A.

I/O Bus

The I/O bus is a parallel backplane bus designed for the fast interchange of I/O signals. Each rack has an I/O bus. Time-critical operations to access the process data of the signal modules take place via the I/O bus.

Communication Bus (C Bus)

The communication bus (C bus) is a serial backplane bus designed for the fast exchange of large volumes of data parallel to the I/O signals. Except for racks ER1 and ER2, each rack has a communication bus.

Rack with I/O Bus and Communication Bus

The following figure shows a rack with an I/O bus and a communication bus. The I/O bus connector and communication bus connector can be seen at each slot. When the rack is delivered, these connectors are protected by a cover.

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I/O bus connector

Communication bus connector

Automation System S7-400	Hardware and Installation	2-7
A5E00850741-01