take input from a rs232 and execute in the matlab

Hello every one the question looks very simple .I will clearly explain my problem

I am new to this interface part of matlab

the problem is I had a RFID card reader (<http://www.simpaltechnologies.com/low_cost_rfid_reader_kit_rs232.html>) the reader has an rs232 out put now i want to know which rfid card was scanned by the rfid reader and then use the respective card number as an input to a written programe in matlab and take the output from the result programme and send it via usb and this process in continous.

please explain me in clear.