The OPC Foundation announced the publish/subscribe model in 2018, which is a content-based transmission method. Each content has a topic, which can be subscribed by topic in the intranet. When a topic is published, subscribers can receive messages regarding this topic immediately. It defines two different network types, one is a local network, using UDP text broadcasting. The other is a message queue broker protocol, which can be brokered by MQTT or AMQP and published in JSON format. In the past, Industry 3.0 had the famous automation pyramid developed to Industry 4.0, at this stage, factory equipment can be networked and crucial production information can be transmitted.
The Opc Ua unified architecture provides the following integrated content:
- Real-time data access specification (Opc Da): It mainly collects real-time data on the equipment side and transmit it to the remote storage system by DCOM, such as MES, SCADA, etc.
- Historical data access specification (Opc Had): For the historical data that has been archived on the device side, it is transmitted to the analysis application.
- Warning event prompt specification (Opc A&E): It can define the transmission rules of warning events and the conditions of variables.
OPC security protocol Integrate all the dispersion provided by OPC in the past into Opc Ua.