If you want to implement a ModBus slave, using a ModBus master software is probably not a good idea.
I am using arduino v1.0.1
Get a more recent version, 1.0.5 is current.
Google Code Archive - Long-term storage for Google Code Project Hosting.
Google Code Archive - Long-term storage for Google Code Project Hosting.
You still didn't tell us what didn't fulfill your requirements in these two implementations. You also didn't specify what these requirements are.
AMPS-N:
I wanted to impliment like this:http://replicantfx.com/wp-content/uploads/2012/11/ModBusSlave_Ref.pdf
This project already includes software for the Arduino, although it's for a pre-1 version of the IDE, but the required changes are simple and small (described in the playground).
This project uses Mach 3 on the PC. Do you own that software? If not, what other software do you plan to use on the PC?