Siemens Simatic S7-300 CPU 31xC Series User Manual

Addressing
7.2 User-specific addressing of modules
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05
7-3
7.2 User-specific addressing of modules
7.2.1 User-specific addressing of modules
User-specific addressing means that you can assign an address of your choice to any
module (SM/FM/CP). The addresses are assigned in STEP 7. There you specify the module
start address that forms the basis for all other addresses of the module.
Advantages in user-specific addressing:
• Optimization of address space, due to the exclusion of "address gaps" between the
modules.
• In your standard software configuration, you can define addresses which are independent
of the relevant S7300 configuration.
Note
User-specific addressing of modules is always required when using PROFIBUS DP or
PROFINET IO field devices. There is no fixed slot addressing for such a configuration.
7.2.2 Addressing digital modules
This section describes how to assign addresses to digital modules. You need this
information in order to be able to address the channels of the digital module in the user
program.
Addresses of digital modules
The address of an input or output of a digital module consists of a byte address plus a bit
address.
Example: I 1.2
The example consists of:
• input I,
• byte address 1 and
• bit address 2
The byte address is based on the module start address.
The bit address is the number printed on the module.

Siemens Simatic S7-300 CPU 31xC Series Specifications

General

Series	S7-300 CPU 31xC
Power Supply	24 V DC
Communication Interfaces	MPI, PROFIBUS DP
Programming Languages	LAD, STL, FBD, SCL
Operating Temperature	0°C to +60°C
Memory	48 KB - 512 KB
Dimensions	40 x 125 x 130 mm (varies by model)