9-2
8 SERIES PROTECTIVE RELAY PLATFORM – COMMUNICATIONS GUIDE
OPC–UA ARCHITECTURE
CHAPTER 9: OPC–UA COMMUNICATION STANDARD
OPC–UA Architecture
OPC-UA is a platform-independent standard through which various systems and devices
can communicate by sending messages between Clients and Servers. It supports robust,
secure communication that assures the identity of Clients and Servers and resists attacks.
OPC-UA defines sets of Services that Servers may provide, and individual Servers specify
to Clients which Service sets they support. Information is conveyed using OPC-UA-defined
and vendor-defined data types, and Servers define object models that Clients can
dynamically discover. Servers can provide access to both current and historical data, as
well as Alarms and Events to notify Clients of important changes. OPC UA can be mapped
onto a variety of communication protocols and data can be encoded in various ways to
trade off portability and efficiency.
The OPC communication is done through Client-Server architecture. In the case of the 8
Series relays, the relay is implemented as the Server.
NOTE
NOTE:
An OPC-UA Server is only available in 8 Series relays with an Advanced Communications
option.
The parts that are supported are:
•
OPC-UA DA
–
Read and write actions of the data service. The data service deals with real-time
data only, not historical data.
•
OPC-UA AE
–
Alarms and events service.
•
OPC-UA Methods
–
Commands service.