Difference Between Modbus TCPIP And Ethernet IP

1st  April, 2025.

In this post, we will see the difference between Modbus TCP IP and Ethernet IP.

If you are an industrial automation engineer, it is very important to be prepared in industrial communication protocols for working in this field. As automation is going more and more towards soft methods and depending heavily on communication protocols, it is necessary to have a brief understanding of the various methods used. Two of the most used protocols in industrial automation are Modbus TCP and Ethernet IP. It is important that the engineers know how they differ in their working, so that they can choose the correct one for their application. In this post, we will see the difference between Modbus TCP and Ethernet IP.

What is Modbus TCP IP protocol?

Originally developed by Modicon in the form of Modbus RTU which is most commonly used in RS485 or RS323 serial lines, Modbus TCP IP is an extension of Modbus RTU, which uses Ethernet as hardware. Due to this, you need to configure all the Ethernet settings like IP address, gateway and all. So, similar to Modbus RTU, Modbus TCP IP also works on master-slave architecture, where the master first requests for data and the slave responds. If any of the master or slave is not working, then communication is not active in the line. It also follows function codes and register addressing format, which is the base of Modbus. The only difference between traditional Modbus RTU and modern Modbus TCP IP protocol is that TCP Ip uses Ethernet hardware, which makes it faster and easier to use. 

What is Ethernet IP protocol?

Ethernet IP too, as the name denotes, works on Ethernet layer hardware. But, there are major differences in it’s working as compared to Modbus TCP IP. Ethernet IP is an object oriented model, working on publisher consumer architecture. That means, data will be continuously transmitted by the slave, irrespective of whether the master is present in the network or not. If present, the master will just listen and use when required. Ethernet IP is built on CIP (Common Industrial Protocol, which is a hardened way of structured data being communicated efficiently. So, Ethernet IP is a real time communication, which is way faster than Modbus TCP IP, which relies on polling mechanism as per Modbus standards. 

Modbus TCP IP vs. Ethernet IP:

1. Real Time Communication:

Modbus TCP IP is not a real time communication, as it works on polling mechanisms. If the master is not present to give a request or a slave is not present to give a response, then the communication will not happen. But, Ethernet IP is a real time communication. It does not depend on whether a master or slave is present in the network. A producer or slave will transmit data in fixed time intervals, and it is not compulsory that a master or consumer must be present in the network to listen to it. If a master exists, it will listen to it and depending on it’s configuration, it will either use it or not. This is a periodic update by the slave, and in case of event driven update, the slave will throw data in case of a triggered event, and will not see if master is present in the network or not. As soon as the consumer comes into the network and is programmed to use data from the producer, it will start to get data in real time. But, if the producer itself is not present in the network, then the consumers waiting for data will throw communication timeout errors in their program. But, this will not affect the overall communication bus network. 

2. Simplicity:

Modbus TCP IP is very easy to use and configure. Even small sensors nowadays have Modbus TCP IP protocol embedded with it, as it makes use of Ethernet hardware, which is easily available and easy to configure. So, many third party vendors implement this protocol as it is ready to use in most cases. Ethernet IP, on the other hand, is not widely implemented by third party vendors as it is difficult to configure and requires skilled engineers to use them having knowledge in class instance, network settings, cyclic messaging and CIP object model. 

3. Data Handling:

Modbus TCP IP, as discussed earlier, uses function codes, register addresses, and uses a maximum of 16 bits for each address. But, as Ethernet IP is based on CIP protocol, it uses predefined objects, attributes, instances, and classes. This makes data more structured or simply, configured in a group manner. A device using Ethernet IP as a producer can store multiple attributes in a single object, and makes it easy for programming. Also, a data object can use even more than 32-bit for a single object in Ethernet IP. So, as you know, a floating point data in Modbus TCP IP consumes two 16-bit registers; but Ethernet IP will give this same data in a single object, be it how many bytes. So, Ethernet IP is designed for robust and complex data handling.

4. Scalability:

Modbus TCP is difficult to scale for large networks, as it works on master slave architecture. You need to carefully consider the total number of devices in slaves, as the master has a limitation for accessing them in total numbers. Also, as it works on polling mechanisms, with an increase in the number of devices, the response time too will increase, which will result in lagging. So, Modbus TCP is best suited for small or medium scale applications having a limited number of devices. Ethernet IP on the other hand is designed for large or ultra large networks, as it is real time and not dependent on whether a master or slave is present in the network or not. N number of producers and consumers can be added in the network, without overloading it. 

5. Security Features:

Modbus TCP IP has very weak security features, as it is open and easy to use. So, it is more vulnerable to cyber security attacks in the network, as there is no authentication or encryption in it. But, Ethernet IP has advanced cybersecurity features in it which looks into authentication (cryptographic), encryption (IPsec or TLS), good access control techniques (role based), and also secure session keys (which will not allow for duplicate or replica sessions by hackers). So, systems where security is not a concern uses Modbus TCP IP, as compared to Ethernet IP which is preferred for critical applications.

I have covered some general differences between Modbus TCPIP and Ethernet IP. I have also not attempted to cover all the topics, as it can vary from case to case. Once you are familiar with this guide, you can easily tackle all types of problems in it.

Thank you for reading the post. I hope you liked it and will find a new way in this type of technology.