port overrun error while reading data in queue

I am trying to read data from various wireless sensors(5-6 in number)  which are communicating with my PC using rs232 port.

the size of data from each sensor that i am getting is 39 bytes.

I want to extract some bytes of these data for which i am using a string subset function.

Now the issue is due to the high baud rate i am not able to read data from each of them individually because before one set of data is worked on another set arrives and port overrun error occurs.

I am trying to do this using queue but could not find a possible solution.