This is free, crossplatform, multilanguages and opensource Modbus-TCP client.
Download: https://bitbucket.org/heXor/openmodbustool/downloads
Feature:
- ModbusTCP master
- ModbusTCP slave (test server)
- IPv6 support
- Read and write registers
- View mode: dectimal int, dectimal signed int, hex, bin, float, double float, word and byte swap
- multiselect, clipboard copy and paste, massive write to registers
Note: ModbusTRU not support (work in progress).
Screenshots and documentation: https://bitbucket.org/heXor/openmodbustool/wiki/Home
Source code (main reposytory): https://bitbucket.org/heXor/OpenModbusTool