OPC UA enables a simple and effective solution for users requiring communication between on-site machines and upper layer management / SCADA systems. This proven technology is easy to implement and well supported by SCADA and enterprise management software. The OPC UA feature allows users to leverage our extensive library of protocol drivers to connect new or existing equipment to a secure, reliable management network.


OPC UA (Unified Architecture) is the next generation of OPC, featuring cross-platform interoperability, high security, and proven reliability. Developed by the OPC Foundation, it is a machine to machine communication protocol for the industrial automation industry and retains all the core functions of OPC, effectively reducing the cost of system integration and allowing for data transfer between the onsite machines and upper layer management systems while still being firewall friendly.

OPC UA is supported by many SCADA, MES, and ERP software providers and uses a Client/Server architecture. This protocol has built-in security with signed and encrypted data transfer using state-of-the-art encryption algorithms. Data is organized into objects, making it easy to access and quickly understand what the data represents, and how to use it.

OPC UA allows client and server applications to communicate with each other. This is key for supervisory control, eliminating the use of Windows-based intermediate systems to streamline the data transfer process from the field and control levels vertically to the management and enterprise levels.

How OPC UA Works

OPC UA is, like its factory floor cousins, composed of a client and a server. The client device requests information. The server device provides it. But what the OPC UA server does is much more sophisticated than what an EtherNet/IP, Modbus TCP or PROFINET IO server does.

OPC UA is designed to be well-suited for connecting the factory floor to the enterprise. Servers can support the transports used in many traditional IT type applications. Servers can connect with these IT applications using SOAP (Simple Object Access Protocol) or HTTP (Hypertext Transfer Protocol).

An OPC UA server models data, information, processes, and systems as objects and presents those objects to clients in ways that are useful to vastly different types of client applications. Better yet, the OPC UA server provides sophisticated services that the client can use.

Features & Benefits of OPC UA

Most other technologies are designed for a specific application. OPC UA is more flexible in that it provides connectivity advantages for all levels of the automation architecture. This architecture ensures seamless device integration in any application to provide a standard communication interface, as it integrates real time data from different devices.

Cross-Platform: OPC UA uses standard TCP/IP to communicate, enabling OPC UA clients to operate on Linux, Windows, Mac, iOS and Android operating systems.

Tag Structure: OPC UA transmits all available tags on connection which can be clearly displayed and browsed, freeing you from memorizing addresses. Information can be conveyed using OPC UA-defined and Vendor-defined data types.

High Security: Robust security model (default end-to-end encryption between Client devices and Server with TLS/SSL certificates). OPC UA uses certificates to authenticate clients and encryption to protect the connection. This ensures that your data is protected and maintains confidentiality and integrity.

Subscribe Mechanism: OPC UA clients can subscribe to tag addresses to receive real-time updates from the cMT OPC UA server when data on the factory machine changes. Servers can provide access to both real-time and historical data.

High Reliability: OPC UA uses configurable timeout settings, error checking, and allows for automatic recovery from communication failures. Servers define object models (data types) that clients can dynamically discover.

In the illustrated example of an OPC Unified Architecture, we are running Aveva Edge as our SCADA software on one of our Industrial Panel PCs. The Panel PC is the OPC UA client and is used to access data in the OPC UA Server, running on a supported cMT device, to receive data updates from any of the PLCs connected to the cMT HMI. No additional drivers required. In this environment, the cMT series with a built-in OPC UA server plays a key role as a communication gateway allowing OPC UA clients to access HMI or PLC data by subscribing to tags to receive real-time updates.

Implementing an OPC UA License

The OPC UA license is included in the purchase price of most of the supported models. However, on select models you must purchase a license for each device. This is a one-time purchase for the life of the product.

For step-by-step instruction on setting up the OPC UA license, refer to the EBPro Programming Manual, cMT OPC UA Server Setup Manual or Tech Note 5120 in our Support Center.

Role of the OPC UA Server

The OPC server is a software program that converts the hardware communication protocol used by a PLC into the OPC protocol. The OPC UA server grants access to Client devices that wish to connect. The server publishes notifications to Clients and End Users, monitors Client devices, and collates data according to information models.

Our IIoT Ready HMIs can be configured as an OPC UA server in our free configuration software, EBPro. And all of our HMIs can act as an OPC UA Client. OPC UA licenses are purchased through Maple Systems.

Role of the OPC UA Client

The OPC Client is the counterpart to the OPC Server. The OPC Server can be connected to the OPC Client and read out the data provided by the Server. Since the OPC Servers implement the predefined interfaces of the OPC standard, each client can access any OPC Server and exchange data with the server in the same way.

Applications acting as OPC Clients

Typical OPC clients are applications that depend on data exchange with industrial systems. What happens to the data in the client is very application-specific. Common applications are visualization and SCADA systems or MES systems. The OPC Router with its OPC UA Client Plug-in is also a client with a gateway function.

The main functions of an OPC UA Clients are:

  1. Client devices request services from OPC UA Server devices. Server devices send response messages and notifications to the OPC UA Client device.
  2. Clients find OPC UA Server devices in multiple ways. Once a Client finds a Server, it obtains the list of available endpoints and selects an endpoint that supports the security profile and transport that matches its application requirements.
  3. Clients begin the process of accessing an OPC UA Server by creating a channel, a long term, a connection between it and an OPC UA Server. Channels are the authenticated connections between two devices. Once the channel is established, Clients create sessions, long term, logical connections between OPC UA applications. A session is the authorized connection between the Client’s application and the Server’s address space.
  4. Clients can subscribe to data value changes, alarm conditions, and any results from programs executed by Servers. Servers publish notifications back to the Client when those items are triggered.
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