Addressing the S7-400

3.2How to Determine the Default Address of a Module

Default Addressing

You determine the default address of a module from the number of the slot of the module in the CR.

The algorithms used to calculate the default address are different for analog and digital modules.

The following figure shows the numbering of slots in an 18-slot rack. You can also read off the slot numbers directly from the rack.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

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5

 

 

 

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11

 

 

12

 

 

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14

 

 

15

 

 

16

 

 

17

 

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Default Addresses of Digital Modules

On the S7-400, the default addresses for digital modules start from 0 (First slot in the central rack which is usually occupied by the power supply module) up to 68 (18th slot).

The algorithm used to calculate the default address of a digital module is: Default address = (slot number - 1) x 4

Example

The default address of a digital module in the 12th slot is as follows:

Default address = (12 - 1) x 4 = 44

3-4

Automation System S7-400

Hardware and Installation

 

A5E00850741-01

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Siemens S7-400 How to Determine the Default Address of a Module, Default Addresses of Digital Modules, Example