Hi Vibhu:
There are two types of uart drivers in MQX, the interrupt mode and polled mode.
If you need to use interrupt mode, please enable relative uart in user_config.h. Let's take uart a for example.
....
#define BSPCFG_ENABLE_TTYA 0 //poll mode
#define BSPCFG_ENABLE_ITTYA 1 // interrupt mode.
.....
Then fopen the uart channel. and receive and send data.
There is an example in MQX package, the rs485 demo demonstrates how to transmit and receive data through rs485 data's channel (ittyd:).
Please refer to the demo for more details.
Freescale_MQX_4_2\mqx\examples\rs485
Regards
Daniel