4. Configuration
123
stored. The SCADA system access the information on
these devices and store on the SCADA server, so that
the SCADA clients can consult it during the plant
operation.
The acquisition network is where the requests for data
collected by field devices travel. to request the data
collected from the field devices.
PLC Communication Gateway
A gateway enables the communication between the
OPC Server and Nexto Series PLCs. A gateway in the
same subnet of the PLC is always necessary, as
described in chapter Communication Settings of
MasterTool IEC XE User Manual – MU299609.
The OPC Server is a Module responsible of receiving
the OPC DA requests and translate them to the
communication with the field devices.
The OPC Client Device module is responsible for the
requests to the OPC Server using the OPC DA
protocol. The collected data is stored on the SCADA
Server database.
The SCADA Server is responsible for connecting to the
various communication devices and store the data
collected by them on a database, so that it can be
consulted by the SCADA Clients.
The supervision network is the network through which
the SCADA Clients are connected to the SCADA
Servers. In a topology in which there aren’t multiple
Client or where the Server and the Client are installed
on the same equipment, this kind of network doesn’t
exist.
The SCADA Clients are responsible for requesting to
the SCADA Servers the necessary data to be shown in
a screen where the operation of a plant is being
executed. Through then it is possible to execute
readings and writings on data stored on the SCADA
Server database.
Table 4-86. Roles Description on an OPC Server Architecture
The relation between the tags on the supervision system and the process data on the controller
variables is totally transparent. This means that, if there’s an alteration on the data areas through the
development of the project, it isn’t necessary to rework the relations between the information on the
PLC and the SCADA, just use the new variable provided by the PLC on the systems that request that
data.
The use of OPC offers more productivity and connectivity with SCADA systems. It contributes with
the reduction of applications development time and with the maintenance costs. It even makes
possible the insertion of new data on the communication in a simplified form and with greater
flexibility and interoperability between the automation system, due to the fact that it’s an open
standard.
The installation of the OPC Server is done altogether with MasterTool IEC XE installation, and its
settings are done inside the tool. It’s worth notice that the OPC is available only with the local
Ethernet interface of the Nexto CPUs. The Ethernet expansion modules do not support this
functionality.
Creating a Project for OPC Communication
Unlike the communication with drivers such as MODBUS and PROFIBUS DP, to set an OPC
communication it’s only necessary to correctly set the node and indicate which variables will be used
in the communication. There are two ways to indicate which variables of the project will be available
in the OPC Server. In both cases it’s necessary to add the object Symbol Configuration to the
application, in case it isn’t present. To add it, right-click over the object Application e select the
option.
To Next Page
Loading...
General