Siemens Communication Services and Protocols - Solutions - Huaqiang Electronic Network

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The concept of Siemens' TIA (Totally Integrated Automation) can be said to be based on communication. Whether it is Profibus or Profinet, or Asi or even Wireless, various communication forms connect different subsystems to form a complete system. The TIA control system, and the services and protocols used in it, can be imagined to be very numerous.
The ISO/OSI model has different layers and different protocols. s7 belongs to the top layer, which is the application layer protocol. It can be loaded on ISO, ISO ON TCP, MPI, PROFIBUS and other networks.
The difference and connection between TCP and ISO/OSI: Strictly speaking, neither of them is a single protocol, but a collection of protocols. ISO is the abbreviation of the International Organization for Standardization. OSI is a framework of the open network system introduced by it. It is like a file cabinet. There are seven drawers, which are divided into physical layer, link layer, network layer and transmission from bottom to top. Layer, presentation layer, session layer, application layer. This is an official guideline for manufacturers to produce products that fit in the appropriate drawers.
TCP is a kind of network framework with facts. It is a file cabinet with four drawers, which are network interface layer (corresponding to the physical layer and link layer of OSI), network layer, transport layer and application layer. This is the framework that precedes OSI and is the standard that most vendors adhere to and is the most widely used.
The two are not contradictory. OSI is a theoretical structure that helps to understand network and communication procedures. TCP is actually a widely used fact structure in this framework. Both played a decisive role in the compatibility of the upper and lower hardware and software products of various manufacturers.
For example, the communication of our Siemens equipment, serial communication at the network interface layer, using the RS422/RS485 standard (note that it is not a network protocol, which is an electrical regulation) and Ethernet communication, using the Ethernet 802.3 standard. Network protocols such as PORFIBUS, MPI, and MDBUS can be used on the transport layer. Network protocols such as TCP/IP, SNMP, FTP, and HTTP can be used on the Ethernet structure. STEP7 and TIA are actually application layer programs that integrate these protocols. Different subnets are generally not interoperable. If communication is to be established, then routing must be done at the network layer and the interface gateway must be set up to communicate.
The difference between S7 communication and S5 compatible communication. If multiple Siemens plcs communicate, it is more appropriate to use S7 compatible communication. Profibus_s7 should be an optimized communication solution for Siemens. We are a host computer manufacturer. When communicating with 300/400 PLC in general, if the first MPI port is occupied, it is often necessary to use the DP port for communication. At this time, based on the Profibus bus. Profibus_s7 communication is one of the most effective solutions. It is the real master-master communication, and it uses 1, 2, 7 layers. Communication is simple, fast and effective.
Profibus_s7 communication between S7-300/400PLC can call the block in the library. The communication between the host computer and Profibus_s7 should be similar to the way of tuning the library. The host computer initializes through the parameters of applicaion and S7_connection. The premise is that you need to set up the virtual site of the pc station in step7 configuration.
The Profbus network et200m and hmi can use the same protocol, such as DP, but the HMI needs to configure the Direct key. Different protocols are often used, the former being Dp and the latter being S7. Communication together lies in the setting of Profibus communication, one is the cyclic communication Dp, and the other is the pulmonary circulation communication S7. Both are the same in terms of communication speed because 12M is on one bus. The efficiency is different. A loop can communicate with the IO, but a loop does not necessarily communicate with the HMI's IO. It may take several cycles.