06/08/26 Thu 8:04am
Communication Protocols for Digital Twins
There are two types of protocols used for DTs
- OPC UA (open platform communication-unified architecture)
- MQTT
OPC UA
Is an industrial standard communication used to securely transfer data between machines sensors PLCs and cloud applications. It is a widely used industry 4.0 communication protocol.
It uses a client server architecture, also supports publish-subscribe architecture.
OPC UA: Server
The server is the device or software that exports data like, sensors, PLCs, robot controller, etc.
The server maintains an address space which is a structured collection of data and object.
OPC UA: Client
The client connects to the server and accesses its data like, a cloud based network or a digital twin.
The client can browse available nodes, read, and write ( if permitted ) values and subscribe to data change
Establishing a Connection
The Client discovers a server and opens a secure channel, Authenticates it ( through password or a certificate ) and creates a session.
MQTT
Message Queuing Telemetry Transport
is a lightweight messaging protocol used by devices, like sensors, computers, apps, or digital twins to exchange small messages over a network.
It was designed for the Internet Of Things, where many devices needed to send messages to each other.
In MQTT the device sends a message through a central server called the “Broker” messages are identified by topics called as “Labels” and receivers ask for topics they care about.
Server ↔ Broker ↔ Client