rapid7/metasploit-framework — pull request #967 by esmnemon (2012-10-25 11:24:27+00:00)
Title:  added a fix for modbusdetect.rb and a new utility modbusFindunitID.rb

a small change in the modbusdetect utility, allowing user to set UnitID/StationID as well as just checking against UnitID=1, which is often the only one.

Since modbus is actually supporting to control UnitID's from 1..255 on a singel IP/port, I've added a utility which is able to determine which UnitID's is enabled.

A well function modbus-slave simulator can be found on http://www.modbustools.com/
and another one on http://plcsimulator.org/