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10 Most Used PLC Communication Protocols in Industry

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Today, we are studying the most used Programmable Logic Controller (PLC) communication protocols in the industry. This article contains the top 10 communication protocols for PLC in detail.

Firstly, you should know…

What is Communication Protocol?

We all know the typical definition of communication protocol.

The communication protocol is a set of rules that govern data communication.

In other words, the communication protocol acts as an agreement between two or more communicating devices.

By using the communication protocols, two devices connect and communicate with each other.

Without communication protocol, devices can only be connected but not communicated.

List of PLC Communication Protocols

Here, I am sharing the list of different types of communication protocols used in PLC.

  • Ethernet
  • Profibus
  • RS-232
  • RS-485
  • Multi-Point Interface (MPI)
  • Point to Point (PPI)
  • Data Highway (DH)
  • Control Net
  • Device Net
  • USB Adapter
  • PC Adapter

These are the foremost protocols used for the PLC and other network connections. These protocols are supported by different PLC software brands.

The communication protocols are dependent upon three fundamental parts as mentioned below.

  1. Baud rate
  2. Network length
  3. Number of nodes

What is the Baud Rate?

Baud rate is also known as “Communication speed”.

The rate of data transmission on the network is called Baud Rate.

In simple terms, it is calculated as the “number of data transferred per second”.

The unit of Baud Rate is bits/second (b/s).

Note: As all the communication happens over the channel in 0 and 1, Baud Rate and Bit Rate are the same.

The main three fundamental parts are described in the below table.

Characteristics of PLC Communication Protocols in Table

When PLC modules are connected over the network, the standard communication protocols are used.

The different types of standard communication protocols support different speed (baud rate), distance(network length) and the number of connecting devices (nodes).

Sr. No.  Protocol Baud Rate Network Length Number of Nodes
1 Ethernet 100 Mb/s Few Kilometers
(based on the type of Ethernet)
2 Profibus 5- 12 Mb/s  15 Km 127
3  RS-232 19.2 Kb/s 10 m 1
4 RS-485 10 Mb/s 1.2 Km 32
5 MPI 19.2 – 38.4  Kb/s 50 m 32
5 PPI 187.5 Kb/s 500 m 1
6 DH 230.4 Kb/s 3.048 Km 64
7 Control Net 5 Mb/s 30 Km 99
8 Device Net 500 Kb/s 0.487 64
9 USB Adapter 57.6  Kb/s 10 m 1
10 PC Adapter 9600  Kb/s 15 m 1

Which PLC communication protocol you should use?

  • If you want to communicate with the more number of nodes with more speed, Ethernet is the best choice. You can read detail about ethernet here.
  • If your network has a length of more than 25 Kilo-meter, you should use the Control Net protocol.

Basic Bit conversion for Baud Rate

Based on the binary system:

Bit is either 0 or 1.
1 Byte = 8 bits
1 Word = 2 bytes = 16 bits
1 Double Word = 4 bytes = 32 bits

This is all about topmost PLC communication protocols. And I also covered the basic fundamental parts of protocol like Baud rate (communication speed), network length and the number of nodes supported by each protocol.

Which communication protocol you use for PLC? Share with me by commenting below. If you have any query, let’s discuss.

Happy PLC Learning!

40 thoughts on “10 Most Used PLC Communication Protocols in Industry”

  1. Thanks for the valuable info.
    .We are using ethernet cat5 utp cable for controller communications to remote control room.

  2. Thanks for valuable information.
    you can send me some PLC questions based on timer,counter,holding ,and project based ?

  3. Please explain me that how can we select a servo motor and its drive in a machine and what are the parameters need to configure to run a servo motor with a drive .

  4. Thank you for your valuable information. Please explain to me, what is the term ‘physical medium’ using in PLC Communication? I have some doubt about the same.

    • Hi Nishida. It is physical Media, not a physical medium.

      In the PLC communication system, we are using physical media to transfer the data information from one place to another and as well for storing data. For these communication data storing and transferring, physical media refer to the physical materials in the form of conducting material.

      There are three different types of Physical media used in a communication system – 1. Copper wire, 2. Optical fiber and 3. Coaxial cable.

      If you have any queries or doubts, you can freely ask me.

  5. Nicely Explained!

    Please, explain how to link or communicate PLC with PLC?
    Which kinds of communication protocols are commonly used and how to address multiple PLCs.

  6. Thank you for your valuable information but I have still doubt in “nodes”? Can you please explain to me with a brief.

  7. Hi, thank you very much for your help, I Want to know what are the references for this table of characteristics of communication protocols.

  8. Nicely explained!

    To understand the Communication protocol your given table is very very useful.

    Thanks a lot for the Characteristic table.


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