The Modbus Utility location:
http://ftp.icpdas.com/pub/cd/8000cd/napdos/modbus/modbus_utility/

or 

The eSearch Utility (v1.1.6 or later) supports "Modbus RTU Master" and "Modbus TCP Master" items in the "Tools" menu
that two programs are useful for testing.
The eSearch Utility location:
http://ftp.icpdas.com/pub/cd/tinymodules/napdos/software/esearch/