How To Determine The Default Address Of A Module - Siemens SIMATIC S7-400 Installation Manual

Addressing the S7-400
3.2

How 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.
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
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