Arduino UNO to modbus connection

Dear Friends and Gurus

I am very new to arduino. After several play with basics. I started the project what i actually want. To connect multiple slave devices from Arduino through RS485. First i connect Rs485 board in arduino and its A and B pin is connected to another usb to rs485 convertor and its is again connected to computer. And the result is amazing with only two line serial code. What i print serial in the arduino is printed in the hyperterminal of the other system.

In the other system now i install the Modbus simulator and set values in Holding register. Using VB and Mod bus dll in some other i able to read that holding register value.

Now i want to Retrive that data into arudino . I use the ModbusMaster.h as mention in Arduino Playground - ModbusMaster Library . In basic i start by checking the holding register. if value is greater than zero the 13 pin led high otherwise low. But even it cant pass node.ku8MBSuccess . Plz that 8 lines code make me mad for last two days.

i search through web for last two days. All of them are very advance. I am just a starter. Any one plz help me. Waiting for your reply. Thanks in advance.

Jegatheesan.S