Communication Protocol of a future: OPC-UA or Modbus?

Industrial automation and control systems have revolutionized how we operate machinery and processes. We don’t need to operate the valves by hand. From one location, we can operate pumps and valves from different systems. Communication protocols play a crucial role in Automation Systems. They allow us to communicate! But what will look like, the communication protocol of the future?

In this article, I will show the differences between two popular protocols: The very well-known Modbus and not so well known yet, OPC UA. These are the two most common communication protocols which You can find in industrial automation and control systems. (Most probably everyone involved in automation systems meets Modbus already). While both protocols serve a similar purpose, they have different approaches to delivering. In this article, I will show You the differences between Modbus and OPC UA, and where is their future.


Modbus is a popular communication protocol used in industrial automation systems. It enables devices such as programmable logic controllers (PLCs) and human-machine interfaces (HMIs) to communicate with each other over a network. There are several different variants of Modbus, including Modbus RTU, and Modbus TCP.

Modbus RTU

Modbus RTU is a serial communication protocol that uses a binary representation of data. This protocol requires low bandwidth and low latency, such as process control and factory automation. Modbus RTU is designed to work over long distances, therefore it is suitable for use in remote applications.

Modbus RTU uses a master-slave architecture, where the master device initiates communication and the slave devices respond. It’s a reliable protocol that can detect and recover from transmission errors. Modbus RTU is also a cost-effective solution as it uses a simple physical layer that requires only two wires for communication.

Modbus TCP

A more advanced version of Modbus is TCP. It is a simple and open protocol. Protocol is very common in communication between programmable logic controllers (PLCs), human-machine interfaces (HMIs), and other automation components. This is one of the industry standards.

One of the benefits of Modbus TCP is its simplicity. It has a straightforward message structure, making it easy to implement in devices with limited processing power. However, it’s not designed for real-time communication, and it lacks advanced security features.

So You know already that Modbus is good, and reliable, but not perfect for all applications. Very simple application, Your choice should go to Modbus RTU. More sophisticated control structure, Modbus TCP. But what if You have a very complex structure, and You need real-time processing, you need to look to:

OPC UA – communication protocol of the future

OPC UA (Unified Architecture) is a protocol developed by the OPC Foundation in the early 2000s. It’s a more advanced protocol than Modbus TCP, designed to provide more functionality and security. (Good thing is that it also provides Safety communication protocol according to IEC standards)

OPC UA is a platform-independent protocol. This means, that this is Android or Windows of Industrial automation. It is definitely not like Apple. It uses a service-oriented architecture, which means that it can provide advanced services such as data modeling, security, safety, and real-time communication.

I have spent last year on the research of Autonomous and Remotely controlled ships. There are still a lot of unknowns, but one thing is clear. We need a very sophisticated automation system, with remote control capabilities. This is why I think OPC UA is the way to go:

OPC UA Safety:

OPC UA provides several safety features. The most important is redundancy in communication. When one of the communication channels fails, You will be automatically informed by the system. There is also a fault tolerance check, to ensure that critical data is transmitted in a reliable way. It also provides mechanisms for secure access control and authentication to prevent unauthorized access to critical data.

Security of communication protocol of the future:

Security features, included in OPC UA are very useful. Encryption, digital signatures, and authentication mechanisms provide security to prevent unauthorized access.

Real-time communication:

OPC UA supports real-time communication, which is essential in industrial automation applications that require quick response times. Data exchange, including multicasting and batching, is all done inside the protocol.

Data modeling:

OPC UA supports a wide range of data types and structures. Including hierarchical structures, arrays, and user-defined types. This allows for easy integration with different devices and systems also from different manufacturers.


Modbus TCP and OPC UA serve similar purposes but have different approaches to achieving their objectives. Modbus TCP is a simple and open protocol, making it easy to implement in devices with limited processing power. However, it lacks advanced security features and is not designed for real-time communication.

OPC UA is a more advanced protocol that provides advanced services such as data modeling, security, and real-time communication. It’s platform-independent and provides advanced security features, making it suitable for use in critical applications. From a hardware point of view, it can be used in PC’s cloud-based servers, PLC, and microcontrollers. Therefore, the platform is really independent and flexible.

Which one should You choose?

It’s actually very simple, and everything depends on the type of application You need to build. For remote interface for a single system, You should use Modbus RTU. For simple SCADA, Modbus TCP will be a good choice. If Your project is very complex and it requires security/safety features, the choice is also quite obvious. You go with OPC UA.


  • Mateusz Białas

    Researcher of Autonomous and Remotely Controlled ships. Since 2014 in Maritime Industry. Experience gained at Ro-Ro, Ferry, Container, and Heavy Lifts, design of Navy Ships.

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[…] some well-established standards like Profinet/Profibus, Modbus, EtherCAT, CANBUS, OPC classic, and OPC-UA. Principals working for all the protocols are the same: They communicate components of the systems. […]

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