Siemens CPU 319-3 PN/DP User Manual

Memory concept
4.1 Memory areas and retentivity
CPU 31xC and CPU 31x, Technical Data
4-2 Manual, 01/2006 Edition, A5E00105475-06
System memory
The RAM system memory is integrated in the CPU and cannot be expanded.
It contains
• the address areas for address area memory bits, timers and counters
• the process image of the I/Os
• local data
RAM
The RAM is integrated in the CPU and cannot be extended. It is used to run the code and
process user program data. Programs only run in RAM and system memory.
Table 4-1 Retentivity of the RAM
All CPUs except: CPU 317, CPU 319 RAM is always retentive.
317 256 KB of RAM can be used
for retentive data modules.
319 700 KB of RAM can be used
for retentive data modules.
4.1.2 Retentivity of load memory, system memory and RAM
Your CPU is equipped with a service-free retentive memory, i.e. its operation does not
require a buffer battery. Data is kept in retentive memory across POWER OFF and
restart (warm start).
Retentive data in load memory
Your program in load memory is always retentive: It is stored on the SIMATIC Micro Memory
Card, where it is protected against power failure or CPU memory restart
Retentive data in system memory
In your configuration (Properties of CPU, Retentivity tab), specify which part of memory bits,
timers and counters should be kept retentive and which of them are to be initialized with "0"
on restart (warm restart).
The diagnostic buffer, MPI address (and transmission rate) and operating hour counter data
are generally written to the retentive memory area on the CPU. Retentivity of the MPI
address and baud rate ensures that your CPU can continue to communicate, even after a
power loss, memory reset or loss of communication parameters (e.g. due to removal of the
SIMATIC Micro Memory Card or deletion of communication parameters).

Siemens CPU 319-3 PN/DP Specifications

General

Brand	Siemens
Model	CPU 319-3 PN/DP
Category	Computer Hardware
Language	English

Summary

Safety Guidelines

Safety Alert Symbols and Grades of Danger

Explains the meaning of safety alert symbols and danger grades (Danger, Warning, Caution, Notice).

Qualified Personnel

Operating and Display Elements

CPU 31xC Operating Elements

CPU 31x Operating Elements

Specific CPU Operating Elements (317-2 DP, PN/DP)

CPU 31x Status and Error Displays

Communication

Interfaces (MPI, PROFIBUS DP, PROFINET, PtP)

Describes available interfaces like MPI, PROFIBUS DP, PROFINET, and Point-to-Point.

Communication Services Overview

Provides an overview of communication services offered by the CPUs.

Routing and DPV1 Communication

S7 Connections and Resources

Explains S7 connection paths, assignment, distribution, and availability of resources.

Memory Concept

Memory Areas and Retentivity

Explains CPU memory areas (Load, System, RAM) and their retentive properties.

SIMATIC Micro Memory Card (MMC) Properties

Memory Functions

Cycle and Reaction Times

Cycle Time Calculation and Factors

Explains cycle time calculation, factors affecting it, and extensions due to communication load and interrupts.

Response Time Definition and Factors

Defines response time and factors influencing it, including shortest and longest times.

Sample Calculations

Technical Data of CPU 31xC

CPU 312C, 313C, 313C-2, 314C-2 Technical Data

Provides detailed technical specifications for CPU 312C, 313C, 313C-2, and 314C-2 models.

Technical Data of Integrated I/O

Covers arrangement, usage, parameterization, and electrical data of integrated I/Os.

Technical Data of CPU 31x

General Technical Data and Dimensions

SIMATIC Micro Memory Card (MMC) Specifications

CPU 312, 314, 315-2 DP, 315-2 PN/DP Technical Data

Provides detailed technical specifications for CPU 312, 314, 315-2 DP, and 315-2 PN/DP.

CPU 317-2 DP and CPU 319-3 PN/DP Technical Data

Details technical data for CPU 317-2 DP and CPU 319-3 PN/DP, including interfaces and functions.