SIEMENS S7-1413 Communication Software Architecture and Application Detailed Explanation

SIEMENS S7-1413 Communication Software Architecture and Application Detailed Explanation

In industrial automation systems, reliable and efficient data communication is the foundation for achieving equipment integration and process control. Siemens SIMATIC NET, as a communication system for automation engineering, provides various high-performance LAN solutions. Among them, S7-1413 serves as an important software component that connects personal computers (PCs) and programming devices (PG) to the SIMATIC S7 control system, achieving data exchange and system integration through industrial Ethernet. This article is based on the official technical manual and provides an in-depth analysis of the architecture features, interface design, and practical applications of S7-1413.

Overview and functional positioning of S7-1413

S7-1413 is a key software in the SIMATIC NET product family, used to enable communication between PC/PG and SIMATIC S7 programmable controllers in the Windows 95/Windows NT operating system environment. Its main functions include:

Protocol support: Supports both ISO Transport protocol (compliant with ISO 8073) and TCP/IP protocol (based on RFC 1006 extension) to ensure good compatibility and flexibility in industrial Ethernet environments.

Unified interface: Provide SAPI S7 (Simple Application Programmers Interface for S7) as the user program interface to achieve standardized communication with SIMATIC S7 system.

Hardware dependency: Must be used in conjunction with Siemens dedicated network adapter CP 1413, supporting multiple network card configurations to meet complex network topology requirements.

S7-1413 is typically applied in the following scenarios:

Equipment status monitoring and parameter modification

Production statistics and process data archiving

Process visualization system

Data acquisition and monitoring system (SCADA)

System architecture and communication network integration

1. SIMATIC NET communication network system

SIMATIC NET is an open, heterogeneous communication system based on the ISO/OSI reference model, providing multiple LAN solutions to meet different levels of automation requirements:

Industrial Ethernet: Based on the IEEE 802.3 standard, using CSMA/CD access technology, suitable for workshop level and management level networks, supporting electrical and fiber optic transmission.

PROFIBUS: A fieldbus that complies with the DIN 19245 standard, used for device level and field level communication.

AS-i (Actor Sensor Interface): A low-level communication network for sensors and actuators.

S7-1413 is mainly integrated into industrial Ethernet environments and can build stable networks using standard SIMATIC NET components such as transceivers, branch cables, fan out units, etc.

2. Structure of software and hardware components

On the Windows 95/Windows NT platform, the software architecture of S7-1413 includes:

Application layer: User defined programs communicate through SAPI S7 or SEND/READIVE interfaces.

Interface layer: SAPI S7 library or SEND/ReceIVE library, providing standardized function calls.

Driver layer: SIMATIC NET driver, managing CP 1413 hardware communication.

Hardware layer: CP 1413 communication processor, implementing physical layer data transmission and reception.

This hierarchical structure ensures the efficiency and reliability of the communication process, while facilitating system maintenance and expansion.

Core programming interfaces: SAPI S7 and SEND/READIVE

1. SAPI S7 interface

SAPI S7 is a C language programming interface for SIMATIC S7 systems, with the following characteristics:

Asynchronous operation: supports non blocking communication and improves system responsiveness.

Automatic connection management: Automatically handle the establishment and release of S7 connections (active/passive mode).

Fault diagnosis: Built in tracking function for easy debugging and troubleshooting.

Multi language support: In addition to C language, it can also be called by languages such as Visual Basic and Pascal through encapsulation libraries.

Rich services: Provides advanced communication functions such as "read and write variables", which are easier to use than underlying interfaces.

SAPI S7 is also available in PROFIBUS networks, ensuring consistent access for programs in different network environments.

2. SEND/RECEIVE interface

SEND/RECEIVE is a programming interface located at the transport layer (Layer 4), primarily used for communication with SIMATIC S5 systems. Its features include:

Direct data exchange: Communicate with the data processing block of S5 by calling interface functions.

Backward compatibility: provides a convenient integration path for existing S5 systems.

Supporting resources: Provide sample programs and call libraries to help developers quickly get started.

3. Development support resources

To reduce programming difficulty, S7-1413 provides the following resources:

Example program: Written in C language, demonstrating interface calling methods and data flow control.

Call library: A static or dynamic library containing interface functions that can be directly integrated into user projects.

Detailed manual: The "S7 Programming Interface" and "SEND/ReceIVE Programming Interface" provide complete API instructions and communication process guidelines.