Siemens Automation System S7-400 User Manual

Page 58

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Addressing the S7-400

3-6

Automation System S7-400 Hardware and Installation

A5E00850741-01

3.3

How to Determine the Default Address of a Channel

Channel on a Digital Module

A channel on a digital module is addressed bit-wise. For a digital input module with
32 inputs, four bytes (starting with the default address of the module) are used to
address the inputs, and for a digital input module with 16 inputs, two bytes are
used. Bits 0 to 7 in these bytes are then reserved by the individual inputs (from top
to bottom).

This is clarified by the following figure with the example of a digital input module
with 32 channels at slot 12 (default address 44). With a digital output module, the
first character is a Q instead of an I.

I 44.0

I 44.1

I 44.2

I 44.3

I 44.4

I 44.5

I 44.6

I 44.7
I 45.0

I 45.1

I 45.2

I 45.3

I 45.4

I 45.5

I 45.6

I 45.7
I 46.0

I 46.1

I 46.2

I 46.3

I 46.4

I 46.5

I 46.6

I 46.7
I 47.0

I 47.1

I 47.2

I 47.3

I 47.4

I 47.5

I 47.6

I 47.7

Channel addresses