4. Configuration
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OPC DA Server
It’s possible to communicate with the Nexto Series CPUs using the OPC DA (Open Platform
Communication Data Access) technology. This open communication platform was developed to be
the standard in industrial communications. Based on client/server architecture, it offers several
advantages in project development and communication with automation systems.
A very common analogy to describe the OPC technology is of a printer. When correctly connected,
the computer needs a driver to interface with the equipment. Similarly, the OPC helps with the
interface between the supervision system and the field data on the PLC.
When it comes to project development, to configure the communication and exchange information
between the systems is extremely simple using OPC technology. Using other drivers, based on
addresses, it’s necessary to create tables to relate tags from the supervision system with variables
from the programmable controller. When the data areas are changed during the project, it’s necessary
to remap the variables and create new tables with the relations between the information on the PLC
with the Supervisory Control and Data Acquisition system (SCADA).
Figure 4-43. OPC Architecture
Figure 4-43 shows an architecture to communicate a SCADA system and PLCs in automation
projects. All the roles present on a communication are explicit on this figure regardless of the
equipment in which it’s executed, since they can be done in the same equipment or in various ones.
Each of the roles of this architecture are described on Table 4-86.
Programmable Controllers and
Field Devices Level
The field devices and the PLCs are where the
operation state and plant control information are
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