The stereo plug is wired to the PC serial port as shown in the following diagram:
tip ring sleeve +---------------------------------+
| |
/-------+-----+--------------+ |
| RxD | Gnd | TxD | 2.5 mm Stero Plug |
\-------+-----+--------------+ |
| |
DB9*: pin 2 pin 5 pin 3 +---------------------------------+
DB9*: Optionally short together pin 4 (DTR) to pin 6 (DSR) and
pin 7 (RTS) to pin 8 (CTS)
The following table also describes the camera cable's wiring:
Camera PC's
Plug DB9* Signal Name Direction
---- ---- ----------- ---------
- 1 Carrier detect (CD) input to PC
tip 2 Receive data (RxD) input to PC
sleeve 3 Transmit data (TxD) output from PC
- 4 \ Data terminal ready (DTR) output from PC
ring 5 | Signal ground (Gnd) -
- 6 / Data set ready (DSR) input to PC
- 7 \ Request to send (RTS) output from PC
- 8 / Clear to send (CTS) input to PC
- 9 Ring indicator (RI) input to PC
* Note that the cable's D-subminature DB9 RS-232 serial port connector
is female. This connector also goes by the historically more correct
name of "DE-9J".
If you are using this cable with the "freeware" from "photopc", then you don't need to "loop-back" wires on pins 4/6 and pins 7/8 of the DB9 connector. However, these wires may be needed for the "official" Olympus Windows software.
Hint: The parts for this cable can be purchased at most any electronics parts store, such as Radio Shack. One option is to buy an audio "patch cable" with a 2.5 mm stereo plug molded onto one end, then cut off the other end and then wire it to pins 2, 3 and 5 of a DB-9 female connector. A quick continuity check with something like a digital volt meter (DVM) will tell you which wires go to which contacts on the stereo plug. All of the DB-9 connectors that I have come across have tiny pin numbers by the contacts to aid you.
Radio Shack sells a number of "flavors" of 2.5 mm stereo plugs, pre-wired patch cables and DB-9 connectors. It is even possible to avoid using a soldering iron for this by using a pre-wired patch cord and a DB-9 connector "kit" with "crimp-style" push-in pins.
To help make the "electrically inept" a bit braver about making their own camera cable, I wouldn't worry too much about possibly getting the wiring wrong at first and damaging something. PC serial ports use RS-232 signaling, which is electrically "robust" in that the inputs and outputs are protected against short circuits and unusual voltages. In my 30+ years of abusing RS232 serial port wiring, I have yet to damage a serial port. (However, you are on your own!)