Heh, it's OK golden_boy, I'm not sad about it, no problem.
Thing probably is, modbus is rather old technology (from what I've read about it) so it's been around a long time and there's lots of information on the net about it, BUT: it appears to be something that is used in very limited areas of work, i.e. embedded devices, and some decidedly obscure industrial applications. So, this does make the potential number of people who can answer this thread, somewhat smaller than say those who can answer a general networking question.
Google showed me quite a number of different websites devoted to modbus technology, and some of those sites offered free software for dealing with modbus. Just google for "Linux modbus" and you get lots of things
I did not see anywhere a ready-made GUI tool (web-based or otherwise) that was free and ready-to-use. What I did see, were Tcl/Tk components, Perl modules, linux shared libraries and some other pieces, which if a person knew what they were doing (somebody using this modbus in their field of work would perhaps know how to use this stuff) could rather easily be used to create their own GUI.
As for the commandline "GUI", I would think that the Perl module(s) and a bit of wrapper code, you could scratch together a command-line version of the software interface you seek.
Best of success - perhaps when you get down to more specifics about maybe *using* some of the code available, to come up with a chunk of code that works for you, there will be more people who can help!
Kind regards,
Sasha
