Communication via Ethernet CPs in S7 Stations

1.6FETCH/WRITE Services (Server)

Application

In addition to the SEND/RECEIVE interface, the FETCH/WRITE functionality provides further services for S5-compatible communication on configured transport connections.

The FETCH/WRITE interface is used primarily to attach SIMATIC S7 to SIMATIC S5 and to other non-S7 stations (for example PCs).

SFETCH

The partner on the connection (SIMATIC S5 or non-S7 station) can read system data on the SIMATIC S7 PLC.

SWRITE

The partner on the connection (SIMATIC S5 or non-S7 station) can write system data on the SIMATIC S7 PLC.

From the point of view of the SIMATIC S7 PLC, this is a passive communication function; the communications partner initiates the connection establishment.

For further information, refer to the system documentation of the SIMATIC S5 PLC or the non-S7 station you are using.

Connection Types

To access a station with FETCH or WRITE functions, a FETCH passive or WRITE passive connection must be configured. The following types are possible:

SISO Transport

SISO-on-TCP

STCP

Coordinating Access Using the User Program

To coordinate access, you can use the FCs AG_LOCK and AG_UNLOCK.

With these FCs, you can coordinate access to system memory areas so that no inconsistent data are created and transferred.

SIMATIC S5

On the SIMATIC S5 station, the FETCH/WRITE services are configured and started by READ ACTIVE/PASSIVE and WRITE ACTIVE/PASSIVE.

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SIMATIC NET NCM S7 for Industrial Ethernet

C79000-G8976-C129–06

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Siemens S7 appendix FETCH/WRITE Services Server, Connection Types, Coordinating Access Using the User Program

S7 specifications

The Siemens S7 series represents a cornerstone in the realm of programmable logic controllers (PLCs), developed by Siemens, a leading company in industrial automation. Widely used across various industries, the S7 series offers robust solutions for controlling machinery and processes, thanks to its reliable performance, flexibility, and scalable architecture.

One of the key features of Siemens S7 PLCs is the modularity of their design. Each system can be configured to meet specific application requirements due to the ability to mix various input/output modules, CPUs, and communication processors. This modular approach allows for the customization of systems to suit diverse automation tasks, providing end users with the adaptability required for modern manufacturing environments.

The S7 series encompasses several models, including the S7-1200, S7-300, and S7-1500. The S7-1200 is particularly suited for small to medium-sized applications, offering a compact design and integrated communication interfaces. In contrast, the S7-300 is designed for more extensive and complex control systems, making it ideal for large-scale industrial applications. The S7-1500 stands out with its advanced performance metrics, rich feature set, and high-speed processing capabilities, making it perfect for demanding applications that require real-time control and extensive data handling.

Siemens also emphasizes the importance of communication technologies within the S7 series. With options such as PROFINET, PROFIBUS, and EtherNet/IP, the S7 PLCs can seamlessly integrate into existing automation infrastructures, ensuring smooth data exchange between devices. The incorporation of web-based technologies and cloud connectivity further enables remote monitoring and control of systems, enhancing operational efficiency.

Another notable characteristic of Siemens S7 PLCs is the use of TIA Portal (Totally Integrated Automation Portal), an innovative software platform that simplifies the engineering process. TIA Portal allows users to program, configure, and diagnose their automation devices in a single environment, reducing setup times and improving productivity.

In conclusion, the Siemens S7 series stands out due to its modular design, range of models suitable for various applications, advanced communication technologies, and user-friendly programming software. This combination of features and characteristics makes S7 PLCs a preferred choice for industries seeking reliable and efficient automation solutions. As industrial demands continue to evolve, Siemens S7 PLCs remain at the forefront, adapting to technological advancements and setting benchmarks in the automation field.