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Modbus Data Scanner - Extended Guide

Olga Weis Olga Weis

If you're looking for a reliable communication protocol for industrial networks, Modbus should be your top choice. In this article, we'll explain why. Additionally, we'll introduce you to the Modbus Scanner software, which provides a simple and convenient way to retrieve coils, inputs, holding registers, and input registers from Modbus-enabled devices.


  1. Modbus protocol Scanner software
    1.1. How to scan Modbus data
    1.2.Key features of the serial port scanner app
  2. How to provide communications on industrial networks
  3. Modbus solution
    3.1.Modbus ASCII and Modbus RTU modes
  4. Modbus usage fields

Modbus Scanner software

Modbus Scanner is a professional parser of Modbus RTU and ASCII protocols. The software scans Modbus protocols and allows recording and analyzing them at your convenience.
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If you work with Modbus protocols and have an instrument or device that you can connect to your PC's COM port, chances are you may need to collect the serial data you receive for its further analysis. Modbus Scanner (aka Serial Port Monitor) by Electronic Team is a universal professional utility that can easily help you accommodate almost any serial instrument with an RS232 port. This dedicated software is an optimal way to interpret or parse the messages received from or sent by your equipment.

When a device sends a message it usually contains all sorts of extra characters and codes.

Note: What Modbus Scanner does is help to extract the relevant data from each message. The app is designed to decode Modbus ASCII and Modbus RTU data received and sent through the system’s COM ports.

The program allows displaying the incoming and outgoing serial messages in the most convenient and readable format. In addition, the software comes with an advanced built-in search option and unique stream filtering tools with presets.

How to scan Modbus data:

Here’s how you can start a monitoring session and sniff a data using the simple Modbus RTU and ASCII scanner software:
Start Serial Port Monitor on your computer.
Select “Session -> New session” on the main menu.
 New session
Then you’ll see the “New monitoring session” window. In this window, you can choose the visualizers that will display the serial data throughout your monitoring session.
 New monitoring session
Select the “Modbus view” to see the received and sent Modbus data (RTU and ASCII) right on the screen.
 Modbus view
Then, you go to the capture options: select which events to capture – Create/Close, Read/Write, Device Control.
Finally, click “Start monitoring” to activate a new monitoring session. That’s it!
Once you started the monitoring session with the Modbus view, you can set the required configuration in the viewer’s preferences.
To do this, you should go to “Session -> Preferences”;
 Table view

Choose the color for date time, header, structure, details, checksum, and errors. Then, select whether to scan Modbus data as Modbus RTU or Modbus ASCII.

“I used this software and found it to be incredibly user-friendly. It met all my expectations. As an electronics engineer, I used the software to analyze and communicate with my domestic devices, such as my VMC. I am planning to create a display and control module using this application. Additionally, I used it at work on industrial equipment. As a maintenance technician for radioactivity detection and monitoring equipment in nuclear power plants developed by the MIRION company, we use a Serial Port Monitor to scan Modbus RTU data.”
(AMBROSINI Frédéric)

Key features of the COM port scanner app

Modbus ASCII and RTU Scanner have proved to be efficient tool for tracking down possible problems during the development of serial applications and drivers, testing and optimizing serial devices, etc.

This professional RS232 and RS485 sniffer offers a host of advanced features, including:

✅The ability to start reading a COM port that is already in use by another program. All data received by the sniffer interface is shown in real time so that a programmer can identify any possible issues.

✅The ability to monitor multiple RS232, RS422, and RS485 ports simultaneously. If you need to analyze the activity of several Modbus ports within one session, you can easily do this with the Modbus message parser app. Data flowing in and out of the port is conveniently recorded in a single log using the first-in-first-out method.

✅Support for several data viewing modes: table, terminal, line, dump, and Modbus visualizers. You can use all or several of them at a time. More than that, various filters offered by this utility will also serve for precise monitoring.

✅Emulation of the data transfer to a serial device in order to see the exact reaction of the device to specific commands.

How to provide communications within industrial networks

As a result of constant modernization of production, today more and more industrial automation systems are based on distribution networks working over flexible data transfer protocols.

There’s a wide variety of interfaces and data transfer protocols that provide communications within industrial networks. These include Modbus, Ethernet, CAN, HART, PROFIBUS, etc. They allow data transfer between sensors, controllers, and actuators; calibration of sensors; power supply to sensors and actuators; communication between the lower and upper levels of the process control systems, and more.

The data transfer protocols are usually developed according to the requirements of a particular production and technical systems and provide a reliable connection and high accuracy of data transfer between different devices. Along with the reliability of operation in harsh conditions, ACS TP systems often require high functional capabilities, flexibility in construction, ease of integration and maintenance, and compliance with industry standards.

Modbus solution

Modbus protocol is widely used as a communication channel between automation elements in industrial data networks. There are three main implementations of the Modbus protocol. Two of them are designed for serial data communication over both copper EIA/TIA-232-E (RS-232), EIA-422, EIA/TIA-485-A (RS-485), and optical (and radio) lines: Modbus RTU and Modbus ASCII. And one of them is for data transmission across Ethernet networks: Modbus TCP.

Modbus solution

Modbus ASCII and Modbus RTU

The difference between Modbus ASCII and Modbus RTU protocols lies in the way they encode characters. In the ASCII mode, the data is encoded using an ASCII table where two bytes of data correspond to each character. In the RTU mode, the data is transmitted in the form of 8-bit binary symbols, which provides a higher data rate. With ASCII there can be a delay of up to 1 second, unlike RTU, where messages must be continuous. Also, ASCII mode has a simplified system of data decoding and management.

Modbus ASCII and Modbus RTU

Modbus protocols (Modbus ASCII, Modbus RTU, and Modbus TCP) use one application protocol to ensure their compatibility. The maximum number of nodes in the Modbus network is 31. The length of communication lines and the data transfer rate depend on the physical implementation of the interface. All elements of the Modbus network interact using a client-server model based on transactions consisting of a request and a response.

Where Modbus is used

Areas of Modbus industrial application: communication of sensors and actuators with the controller, communication of controllers and control computers, communication with sensors, controllers, and corporate networks, connections in SCADA systems, etc.

The simplicity of implementing Modbus protocols has led to its wide application in industrial systems and not only. Today the equipment of almost all manufacturers comes with support for Modbus protocols.

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