Epson PhotoPC 700 Serial Cable

A little "reverse-engineering" of the serial cable supplied with the Epson PhotoPC 700 camera by Dave Wilson ( revealed the following facts. The connector on the camera end is a 8-pin "mini DIN". This connector was used on early Apple Mac computers. (It is not the same connector used on "PS-2" mice and modern PC keyboard cables, which are 6-pin mini-DINs.) The other end is a standard 9-pin female D-subminature connector (a.k.a., DB-9), and is normally plugged into a PC's 9-pin serial port.

The pins on the camera's female mini DIN connector and the PC's male DB-9 connector are numbered as in the following diagrams:

Note: The above diagrams show the relative pin positions when looking at the connectors on the camera and on the PC, respectively (i.e., these are what the camera cable plugs into). Alternatively, one could view these as diagrams of the back-side of the cable's two connectors.

According to Dave pins 1 through 8 on the mini DIN are wired to pins 1 through 8 respectively on the DB-9 serial port connector, as follows:

      Camera-end        Computer-end
    Male Mini DIN-8   Female DB9 Serial
    ---------------   -----------------
          1               not used
          2                  5
          3                  2
          4                  5
          5                  3
          6                  5
          7                  5
          8               not used        
For those of you that are curious, the following shows the signal pins/names for the DB9 serial connector at the "computer end" of the cable.
   DB9     Signal Name                Direction
   ---     -----------                ---------
    1       Carrier detect (CD)        input to PC
    2       Receive data (RxD)         input to PC
    3       Transmit data (TxD)        output from PC
    4       Data terminal ready (DTR)  output from PC
    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
You can see from the table that only pins 2 (RxD), 3 (TxD), and 5 (Gnd) are important. Clearly pins 2, 4, 6 and 7 of the DIN connector at the "camera end" are grounded.

Apparently, Dave made his PhotoPC 700 serial cable from an Apple mouse-to-serial cable he found in a computer store. This cable had a PC DB9 female on one end and the correct male mini DIN-8 on the other end. He cut the cable in half in the middle, determined what wires went where with an ohm meter, then shuffled the wires as required and connected them back together in the middle of the cable. This saved him a cool $50 over what Epson wanted for a new factory-made cable.

Bruce D. Lightner, last updated Sat Nov 8 09:13:51 PST 2003 .