smod is a modular framework with every kind of diagnostic and offensive feature you could need in order to pentest the modbus protocol. It is a full modbus protocol implementation using Python and Scapy. This software can be run on Linux/OSX under python 2.7.x.
You can download it from the following link: https://packetstormsecurity.com/files/download/135257/smod.zip
Source: https://packetstormsecurity.com/files/135257/smod-Modbus-Assessment-Framework.html