Can we handle multipil slaves at a time ( using modbus protocol ) with labview

[Nagaa]

How to code this program in a simple way

[jyang72211]

Have you looked at the MODBUS library in LabVIEW?  See below.  One of the cluster input will allow you to change the slave id for multiple slaves.  

http://zone.ni.com/devzone/cda/epd/p/id/4756