Communication by OPC interface
(Open Platform Communications
) is the standardized specification of the communication interface for applications that are addressed to monitoring and control processes.
This specification is defined and updated by the organization OPC Foundation
The specification has the client-server architecture.
There are two specifications for data transfer in the OPC
2. OPC DA (DA = Data Access)
This older specification is built on standards COM
by the Microsoft
The main disadvantage of this specification is its dependence on the Microsoft
standards and very difficult configuration in situations if the OPC
server is not located on the same computer as the running PROMOTIC application (then it is necessary to configure DCOM
- see Configuration of the DCOM interface for OPC-DA server
For this OPC
specification there is the PmaOpcDaClient object
in the PROMOTIC system.
More details see Communication by OPC DA interface
The specification includes data sharing (OPC DA
) and also:
- alarms and events sharing (OPC Alarm and Event Handling)
- historic trends sharing (OPC Historical Data Access), etc.
These additional functions are not supported in the PROMOTIC system.