How to capture Modbus TCP/UDP data packets in practice

[jfyes]

As a hardware engineer, after seeing that CEIWEI recently released a new tool for Modbus RTU Over TCP/UDP filtering and monitoring, I actively went to its official website to take a look. It turned out to be a Modbus protocol TCP/UDP packet capture tool. Knowing that his CommMonitor serialPort Monitor also has this function is simply good news for us industrial control dogs, because the free version can also be used permanently.

The following uses Modbus RTU TCP as an example to explain how to capture Modbus TCP/UDP communication data packets. Because CEIWEI ModbusMonitor is a fully parsed Modbus protocol, the monitoring results are obtained, so there is no need to second-guess the TCP/UDP packets yourself. analyzed.

Download and install CEIWEI ModbusMonitor filtering and monitoring tool, http://www.ceiwei.com/down/CEIWEI_ModbusMonitor_20223.zip

Main functions of ModbusMonitor monitoring wizard:

· Support monitoring network port type: TCP/UDP port;

· Can monitor and collect Modbus 502 port data in real time;

· Support monitoring views: list view, Line view, Dump view, terminal view;

· Supports monitoring of all Write/Read data streams of the parallel port;

· Supports customized monitoring view data record colors, time formats, byte line feed lengths, byte display output in different numeric systems, etc.;

· Support monitoring session management: save and load all monitoring data, export and redirect to files;

· Support monitoring view data export to Ansi, Unicode text, HTML, CSV, and support automatic redirection to files (requires enterprise version registration);

· Copy all recorded data to the clipboard (requires enterprise version registration);

· Supports data linkage display between list view, line view, and dump view.



ModbusMonitor monitoring wizard can be used for:

· Monitor data transmission between TCP/UDP network port devices and any Windows App communication;

· Monitor the computer App and connect the device to Modbus TCP/UDP (RTU/ASCII) equipment;

· Can be used for network port program and hardware development and debugging;



ModbusMonitor monitoring wizard for end users

· Software programmers and testers

· Software quality control engineer

· Network Modbus protocol equipment system integrator

· Industrial control and SCADA design engineer



v3.2 change log:



Refactored automatic saving (redirected to file), supports HTML, CSV, Ansi/Unicode text documents,

Optional file split storage method:

Support a single file without splitting;

According to the time range, the log file can be divided and stored in units of hours, minutes, and seconds;

According to the file size, you can optionally split and store the log file in units of MB and KB;

File sizes exceeding the limit will be overwritten.

Support monitoring view log data output as HTML, CSV, Ansi/Unicode text documents;
Online version users, if there is an Internet connection, use the WeChat applet and scan the CommMonitor serial port monitoring wizard QR code, and they will automatically log in successfully;
Online version users, when there is no network, use the WeChat applet to scan the login QR code of the CommMonitor serial port monitoring wizard software, and then enter the authorization login code to verify the login;
Sometimes the exported text of the log string has line breaks. Now, replace the carriage return and line feed characters with /r/n, and there will be no line breaks;
Added USB dongle support;
Other minor issues.