User`s guide

Wonderware Siemens SIMATIC
NET S7 I/O Server
Introduction
The Wonderware

Siemens SIMATIC

NET S7 I/O Server (referred to as the server
through the remainder of this user’s guide) is a Microsoft

Windows

application
program that acts as a communication protocol server. It allows other Windows
application programs access to data within the Siemens SIMATIC S7 300/400 family of
PLCs. The server allows the PC to access a Siemens PLC through the MPI
programming port or a Siemens Communication Processor directly connected to the
SIMATIC S7 300/400 backplane. The server works on the PROFIBUS, H1 Industrial
Ethernet, TCP/IP networks, and supports numerous communication processor cards.
While the server is primarily intended for use with Wonderware InTouch

(version 3.01
and later), it may be used by any Microsoft Windows program capable of acting as a
DDE, FastDDE, or SuiteLink

client.
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 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 our industry, this extension is being pushed to its performance constraints in
distributed environments.
NetDDE

extends the standard Windows DDE functionality to include communication
over local area networks and through serial ports. Network extensions are available to
allow DDE links between applications running on different computers connected via
networks or modems. For example, NetDDE supports DDE between applications
running on IBM

compatible computers connected via LAN or modem and DDE-aware
applications running on non-PC based platforms under operating environments such as
VMS

and UNIX

.