Hello,
I have problem with Software Modbus Doctor, I wanna change the code function of a regestre, but i can't find how. If you have any solution concerning this problem I will be grateful for you.

thank u.

 

The documentation for a free Modbus slave stack (for the AT91SAM ARM-based Flash MCU)
http://www.atmel.com/Images/doc11098.pdf
uses Lamesoft Modbus Doctor as an example of using a Modbus master/client to access the slave. The document has two screen shots of Modbus Doctor.

The screen shot on page 8 shows the function code as the fourth item in the menu bar 'Type' as '4 Input registers' which would be function code 04.

The screen shot on page 9 shows the function code as the fourth item in the menu bar 'Type' as '3 Holding registers' which would be function code 03.

The down arrow next to the Type selection should produce a drop down menu for selection.

 

thank you Mr david,
here is my problem, well as we know that there are some devices can't support all function code, as mine, it can't support the function code =16 writ multiple register, i tried so hard to writing via Modbus doctor on this device but it dosen't work, by against via an other software like modbus poll it work perfectly,so do you know how we can change this code function or it's impossible ...

 

I don't even have a copy of that software, but I suspect that the level of support is typical of freeware, i.e. emailing the listed contact under help > about with an explanation of the symptoms to see if an update might fix it.