thanks for the replies i did a bit of google search and forum search got the required info...
but i come to nderstand that i need to use my arduino as a modbus rtu slave and the parameters or files i recieve from the master need to be transferred to a USB memory stick
the place where i would aply this would send info to the slave board at 250 bytes in intervls of 1 min.
so can i make this work????