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RS-232C is a plain old serial connection not USB. The other models like this camera have USB not RS232C for extracting still images. Chances are a USB<->RS-232 adapter would work if you have the serial cable that plugs into the camera.
This camera does a 4 pin DV(firewire) port also, as I stated above and agreed with the posters before me.
According the manual the RS232C connector on board is a 2.5mm 3 pole jack. The cable plugs into this and ends in a DB9.
Actually if you look at the pinout for a DB9 connector. Pin 2 is receive, Pin 3 is transmit, Pin 5 is signal ground. The other pins are flow control, carrier detection, ring indicator, etc.