Siemens Simatic S7-300 CPU 31xC Series User Manual

Addressing
7.3 Consistent data
S7-300, CPU 31xC and CPU 31x: Installation
7-8 Operating Instructions, Edition 08/2004, A5E00105492-05
7.3 Consistent data
Consistent data
The table below shows you which aspects to take into account for communication in a
PROFIBUS DP master system and in a PROFINET IO system, when transferring I/O data
areas with consistent "full length."
CPU 315, CPU 317, CPU 31xC
The address area of consistent data in the process image is automatically updated.
To read and write consistent data, you can also use SFC 14 and SFC 15. If the address area of
consistent data is not in the process image, you must use SFC 14 and SFC 15 to read and write
consistent data.
Direct access to consistent areas is also possible (L PEW or T PAW, for example).
In a PROFIBUS DP system you can transfer up to 32 bytes of consistent data.
In a PROFINET IO system you can transfer up to 256 bytes of consistent data.

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)