Hi Dilip,
If you do a search on
http://www.ni.com for MODBUS. Lots of examples come up, as well as a MODBUS library for LabVIEW.
I hope this helps!
-Matt S.
LabVIEW Integration Engineer with experience in LabVIEW Real-Time, LabVIEW FPGA, DAQ, Machine Vision, as well as C/C++. CLAD, working on CLD and CLA.