Siemens SIMATIC NET S7-400 User Manual

Configuration and operation
6.3 Recommendation for use with a high communications load
CP 443-1 (EX30)
Manual, 03/2019, C79000-G8976-C255-05
47
6.3
Recommendation for use with a high communications load
Reason
When using the CP described here, the points below will help you to avoid overload
situations on your CPU.
In particular when you replace an older CP with the CP described here and are then
confronted with overload problems, you should check your application for the pitfalls outlined
below.
Known problems
● The program blocks for sending and receiving AG_SEND / AG_RECV (FC5/FC6,
FC50/60 or FC53/63) are often called cyclically in OB1. This leads to constant
communication between the CPU and CP. As a result, other types of communication
such as PG functions cannot be executed or only very slowly.
● HMI systems access data of the CPU too often using S7 functions. This slows down
communication in general and resource bottlenecks on the CPU can occur if
SEND/RECEIVE FCs are called cyclically in OB1 (effect: reduced data throughput or
increased reaction time).
Remedy
Note the following recommendations:
● Do not call communication program blocks cyclically in OB1!
Communication should be called timecontrolled in a suitable cyclicinterrupt OB. The call
interval of this OB should be significantly higher than the average cycle time of OB1.
● You should set a minimum cycle time that is higher than the average runtime of OB1.
This frees resources for communication on the CPU. This is, for example, a solution for
existing applications when communication already takes place cyclically in OB1.
● If necessary, reduce the time taken for communication processing on the CPU by
changing the parameter "Scan cycle load from communication" in the properties of the
CPU.

Siemens SIMATIC NET S7-400 Specifications

General

Brand	Siemens
Model	SIMATIC NET S7-400
Category	Conference System
Language	English

Summary

Properties and Services

CP Core Properties

Details the intended use and interfaces of the Communications Processor (CP).

Enhanced Functions and Compatibility

Covers advanced features and compatibility with older CP modules and firmware versions.

Communication Services Overview

Lists and explains the various communication services supported by the CP.

Additional CP Features and Characteristics

Describes further services and characteristics like media redundancy and time synchronization.

Performance Data

General Performance Characteristics

Provides an overview of general performance data and connection limits.

S7 Communication Performance

Details the performance characteristics of S7 communication protocols.

SEND/RECEIVE Interface Performance

Covers data lengths, connection limits, and call capacities for the SEND/RECEIVE interface.

PROFINET IO and TCP/IP Performance

Outlines performance data for PROFINET IO and TCP/IP communication.

Integrated 2-Port Switch Performance

Describes performance characteristics of the integrated 2-port Ethernet switch.

Requirements for Use

Configuration Limits and System Environment

Specifies configuration limits and system environment requirements for the CP.

Project Engineering and Programming

Details project engineering steps and programming interfaces for the CP.

LEDs

LED Display and Meaning

Explains the front panel LEDs, their display patterns, and meanings for status indication.

Installation and Commissioning

Important Safety and Usage Notes

Covers safety requirements for installation, use in hazardous areas, and power supply.

Installation Procedure

Step-by-step guide for physically installing the CP into the rack and connecting it.

Commissioning Procedure

Outlines the process for configuring and downloading data to the CP.

Configuration and Operation

Security Recommendations

Best practices for system security, physical access, and network protection.

Operating Modes and Load Management

Covers controlling the CP's operational mode and recommendations for high communication loads.

Protection Levels and Configuration

Explains the effects of protection levels and the process for configuring the CP.

Interface Configuration and Settings

Details interface configuration for Ethernet, IP, and network settings.

Diagnostics and Upkeep

Diagnostics Methods (LEDs, Web Server, STEP 7)

Details available diagnostics methods, including LEDs, Web diagnostics, and STEP 7 tools.

Module Replacement and Upgrading

Guides on replacing older modules, covering module replacement and upgrading procedures.

Firmware Updates and Reset Procedures

Covers loading new firmware and procedures for memory reset and factory defaults.

Technical Specifications

Hardware Specifications and Environmental Data

Lists article numbers, Ethernet attachment, electrical data, and ambient conditions.

Design, Dimensions, and Product Functions

Details physical dimensions, weight, module format, and overall product functions.

Certification

Regulatory Compliance and Approvals

Covers EC declarations, ATEX, IECEx, EMC, RoHS, UL, FM, and other regional certifications.

Documentation References

Introduction to Documentation and Finding Information

Guides on locating Siemens documentation, article numbers, and manuals online.

Configuring, Commissioning, and Using the CP Documentation

References for configuring, commissioning, and using the CP, including general applications and history.

Installing and Commissioning the CP Documentation

References for installing and commissioning the CP, including installation and module data.

Configuration with STEP 7 and NCM S7 References

Guides for configuring the CP using STEP 7 and NCM S7, including programming.

PROFINET IO Application and Configuration References

References for applying and configuring PROFINET IO systems.

Industrial Ethernet Network Operation References

Information on setting up and operating Industrial Ethernet networks.