usb serial programming

Not sure if this is the right venue for this question, please direct me to the right place if it's not. I have a C program that opens the serial port /dev/ttyS0 and sends commands (as strings) back and forth to a pan-tilt-zoom camera. That works very well, but I want to use the camera with a Raspberry Pi, which of course does not have a serial port (RS232). One option is to use a RS232 to usb adapter and rewrite the C code for the usb port. So how do I go about that? Is usb serial port programming possible and documented anywhere? Thanks!