Overview
The SIEMENS S7 ETHERNET/MPI Server (hereafter referred to as the “S7ETHMPI Server” or “S7ETHMPI” or “Server”) is a Microsoft Windows application program that acts as a communication protocol Server and allows other Windows application programs to access to the data from Siemens S7-300 and S7-400 controllers using the Ethernet gateway (communication adapter-cable) for MPI, providing interface between 10/100 Mbps Ethernet and Siemens MPI bus. The connection is possible with a hub or switch or Mia a crossover cable directly with PC network card, the used protocol is standard TCP/IP. Any Microsoft Windows program that is capable of acting as a DDE, FastDDE, Any SuiteLink or OPC Client may use the S7ETHMPI Server.
There are two different S7ETHMPI Server versions described in this manual:
- Server version (ordering number DR 470 10), supporting SuiteLink, FastDDE and DDE protocols; this version hereafter is referred to as the “Suite Link & DDE” version.
- Server version (ordering number DR 470 11), supporting OPC and DDE protocols; this version hereafter is referred to as the “OPC & DDE” version;
The separate installation package is supplied for each version of the Server. In both cases, the name of Server executable file is S7ETHMPI.EXE. All further information in this manual is same for all versions of the Server, with the exception of few points where communication protocol specific features are explained.
Note!
The current version 1.02 of S7ETHMPI Server supports only point-to-point connection, i.e. only one PLC can be accessed via one communication adapter-cable.
Communication Protocols
Dynamic Data Exchange (DDE) is a communication protocol developed by Microsoft to allow applications in the Windows environment to send/receive data and instructions to/from each other. It implements a client-server relationship between two concurrently running applications. The server application provides the data and accepts requests from any other application interested in its data. Requesting applications are called clients.
Some applications such as Wonderware InTouch and Microsoft Excel can simultaneously be both a client and a server.
FastDDE provides a means of packing many proprietary Wonderware DDE messages into a single Microsoft DDE message. This packing improves efficiency and performance by reducing the total number of DDE transactions required between a client and a server. Although Wonderware's FastDDE has extended the usefulness of DDE for the industry, this extension is being pushed to its performance constraints in distributed environments.
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