Recently, I needed to check a Modbus TCP server. I went through several client utilities, and I liked one by Schneider most of all:
https://www.schneider-electric.com/en/faqs/FA180037/
It also works with Modbus RTU via the COM port. The only drawback is that it only works with default port 502.
With the ability to specify custom port, I liked the utility:
http://easymodbustcp.net/en/
It has slightly less convenient user interface, and .Net framework should be installed, but there are sources in C #, Java, Python and a DLL in C # so you can use them in your programs.
Here is a direct link to the binaries: https://sourceforge.net/projects/easymodbustcp/files/latest/download
Modscan is another useful utility that allows continuous cyclic reading:
https://www.win-tech.com/html/demos.htm
Modpoll is a nice small command-line utility that supports Linux:
https://www.modbusdriver.com/modpoll.html
