RTOS/LAUNCHXL-CC2650: How to interface cc2650 launchpad with Modbus-RS485(max1348)

Tool/software: TI-RTOS

Hi

I am working on project where I need to send my received udp data to the Modbus here I have used Contiki as SW stack so 

please any one help me out how to send data through modbus.

here I wanted to make my PC as master running some modbus simulator and my cc2650 as slave so 

how can I develop the code to send data through modbus 

suggest any example code if any in contiki or github