SEND/RECEIVE Interface in the User Program

3.1How the SEND/RECEIVE Interface Works on the CPU

Functions (FCs)

The following functions (FCs) are available for handling communication on connections:

SAG_SEND/AG_LSEND

This block takes the user data from the specified user data area and transfers it to the Ethernet CP.

SAG_RECV/AG_LRECV

This block transfers received user data to the user data area specified in the call.

The diagram below illustrates the situation. Using the FCs AG_SEND/AG_LSEND and AG_RECV/AG_LRECV, the user program instructs the Ethernet CP to send or receive data on the configured connection.

Ethernet station SIMATIC S7

 

CPU

Ethernet CP

 

 

CP

 

STEP 7

database

 

user program

 

 

 

User data

 

User data

buffer

 

 

 

areas

 

 

AG_SEND

send

Communication

 

 

 

AG_RECV

receive

connection

 

Figure 3-1 Interaction of the CPU and Ethernet CP on Connections

Amounts of Data

The Ethernet CP can transfer the amounts of data shown in the table below per job on one connection:

Table 3-1

 

ISO Transport

ISO-on-TCP

TCP

UDP

 

 

 

 

 

Sending

8192 bytes

8192 bytes

8192 bytes

2048 bytes

 

 

 

 

 

Receiving

8192 bytes

8192 bytes

8192 bytes

2048 bytes

 

 

 

 

 

74

SIMATIC NET NCM S7 for Industrial Ethernet

C79000-G8976-C129–06

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Siemens S7 appendix How the SEND/RECEIVE Interface Works on the CPU, Functions FCs, Amounts of Data, Ethernet CP

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.