Opc Data Access (Opc Da); Overview; Introduction To The Opc Data Access Interface - Siemens SIMATIC PCS 7 Function Manual

OpenPCS 7 interface

6.3 OPC Data Access (OPC DA)

Synchronous data transmission
When calling synchronous methods, the job is processed completely on the OPC server before
the information is transferred to the OPC client. The OPC server provides synchronous write
and read methods.
Note
You will find the asynchronous and synchronous write and read methods that are available
in the sections "SIEMENS OPC DA Automation Interface 2.0", "SIEMENS OPC HDA
Automation Interface 1.0" and " SIEMENS OPC Alarms and Events Automation Interface 1.0".
6.3 OPC Data Access (OPC DA)
6.3.1

Overview

Overview
You will find information about the following topics in the section below:
● Introduction to the OPC Data Access interface
● How the OPC DA server works
6.3.2

Introduction to the OPC Data Access interface

Introduction
The data access interface is a vendor-independent worldwide standard for reading, writing
and monitoring process data. Communication is based on the Microsoft COM protocol. This
standard has gained acceptance both with users and manufacturers. The user programs, for
example, range from office applications to sophisticated HMI (Human Machine Interface) or
SCADA (Supervisory Control and Data Acquisition) systems.
OPC Data Access (OPC DA)
The OPC Data Access specification defines the interface between client and server programs
for process data communication.
Here, the OPC DA servers allow one or more OPC DA clients transparent access to an
extremely wide variety of data sources (for example temperature sensors) and data sinks (for
example controllers). The following options are typical for connecting data sources and sinks
to automation systems in a PCS 7 plant:
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OpenPCS 7