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S7-400 CPU 41x -- Product information -- Determining performance and quantity frameworks
How can you change the size of the available free main memory of a SIMATIC S7-400 CPU?
How many connections and communication jobs do SIMATIC S7-300 and S7-400 support simultaneously?
Which connection resources are occupied in the S7-400 CPU for communication connections and services of the Industrial Ethernet CP?
How many breakpoints can you insert when debugging a program?
What are the system limits in an F CPU for safe bidirectional data communication using S7 Communication?
How can you determine the size of the load memory and main memory of a SIMATIC S7-300/400 CPU?
Where do you find information on transmission times on the PROFIBUS or Industrial Ethernet?
What is a hardware interrupt and how do they work in the S7-400 system?
What restrictions are there for active jobs when communicating with SFC 58 / SFC 59 and SFB 52 / SFB 53 via PROFIBUS DP and PROFINET IO?
ES - SIMATIC Manager -- Setting up and parameterizing hardware -- Initializing and parameterizing modules
How do the PCS 7 channel blocks behave in the case of a short-circuit to ground of an encoder supply on the digital input module SM321 (6ES7 321-7TH00-0AB0)?
How can you change the size of the available free main memory of a SIMATIC S7-400 CPU?
Why is the active bus module IM153 (6ES7195-7HB00-0XA0) not listed in the English PCS 7 V6.1 documentation?
How do you use a watchdog module of an ET200iSP in PCS 7?
How can I read out the current module status of a SIMATIC Station?
Moving DP slaves to a different master system
How do you start up a SIMOVERT Master Drive SC in PCS 7 V4.0x?
How can you save the configuration of a CP 341 with retroloadable drivers without an online connection to the CPU?
Channel drivers and module drivers in PCS 7 V5.2 for ET 200iS
Why is the system data inconsistent after the CPU has been configured as time slave in HW Config?
Operating master systems (DPV1- and S7-compatible) in one rack
Module driver PA_AI (in PCS 7 V5.2) can only be used to connect IM 157 with MLFB 157-0AA81.. and 157-0AA80..
Selection tool for I/O modules in SIMATIC PCS 7
What should you watch out for with the hardware configuration of the AS CPU?
Configuration of DP slaves
Note on configuring the ET200X (6ES7 141-1BF30-0XB0)
Non-volatile effect with an ET 200M in PCS 7 V5.x
What statuses can the ET 200M outputs have in CPU STOP?
Configuration of Diagnostics Repeater in PCS 7 V6
Diagnostic Alarms of Digital Input Blocks SM 321-7BH00 and SM 321-7BH01
How do you connect a DPV1-compatible PA field device after a DP/PA link DPV1 in PCS 7?
How can you avoid messages with "old" time stamps when commissioning a PLC?
How can you change the size of the available free main memory of a SIMATIC S7-400 CPU?
Part number:

The size of the main memory of a SIMATIC CPU depends on the following parameter settings:

  • Number of messages in the diagnostics buffer of the CPU
  • Maximum number of communication jobs
  • Size of the process-image input and output areas
  • Amount of local data for all priority classes

It is particularly effective to change these parameters with CPU types that have small main memories.

A significant part of the main memory used by the CPU for programs is taken up by the diagnostics buffer of the CPU. Here you have to decide how many messages are required by your application in the diagnostics buffer.

Fig. 1: Setting options for the number of messages in the diagnostics buffer of the CPU

You can also change the number of communication jobs. You can read the requirement in your application in the "Communication jobs of which currently loaded" line (Fig. 4). Change the maximum number as necessary. Here, you must take into account a reserve of approx. 30% is achieved.
You can also change the message texts in this dialog.

Fig. 2: Communication job and local data setting options

If you pay attention to assign the IO addresses of the IO modules as far as possible without gaps, you can reduce the process image for inputs/outputs.

Fig. 3: Setting options for the process image

You can see how the main memory is occupied online in the Properties of the CPU. In the "Memory" tab you select the field with the "main memory code" values (click in the field) and then click the "Main memory details" button.

Fig. 4: Occupation of the main memory of CPU 412

More information about the structure and calculation of the main memory is available in the device manual entitled "Automation System S7-400 CPU Specifications", in the section "Overview of the Memory Concept of the S7-400-CPUs".

Storage capacity, Compression, Safety matrix, Program memory, Code memory

 Entry ID:53843369   Date:2012-01-24 
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