Reading incoming data in serial ports

Hi every body, i have the following problem :

I need to read incoming data from a serial port, this port has connected a weigth device to it that send the weigth and i need to read this data to my aplication, i had this problem in Window Enviroment and i resolve with a "C" routine, but in Unix environment i do not have idea how to do this. If any body can help i really appreciate this.

You can use C to communicate with a serial port under Unix. Here is the Linux HOWTO on the subject:
http://linuxdocs.org/HOWTOs/Serial-Programming-HOWTO.html

The same info. should apply to just about any version of Unix.