Addressing Signal Modules - Siemens SIMATIC S7-300 Hardware And Installation Manual

Addressing
8.5

Addressing signal modules

Introduction
This section shows you how to address signal modules. You need this information
in order to be able to address the channels of the signal modules in your user
program.
Addresses of digital modules
The address of an input or output of a digital module consists of a byte address
and a bit address.
e. g. E 1.2
Input
The byte address depends on the module start address.
The bit address is the number printed on the module.
Insert the first digital module into slot 4 so that it has default start address 0. The
start address of every subsequent digital module will be incremented by 4 per slot
(see diagram under Slot-based module addressing).
The figure below shows you how the addresses of the individual channels of a
digital module are obtained.
8-4
Byte address Bit address
S7-300 Programmable Controller Hardware and Installation
A5E00105492-02