Only this three signal wires are needed in the computer cable.
|Camera cable Pin||Signal||Computer DE-9 cable pin|
|1||Receive data (RxD)||Connect to DB9 pin 2|
|2||Signal ground (Gnd)||Connect to DB9 pin 5|
|3||Transmit data (TxD)||Connect to DB9 pin 3|
You may short together pin 4 (DTR) to pin 6 (DSR) and pin 7 (RTS) to pin 8 (CTS), if needed.