"Steve" wrote in message
...
Ok! Since I haven't gotten any helpful info from Yeoman or otherwise to
determine the pin out of the 4 pin data connector, I took things into my
own
hands..

I opened up the plotter bed for access to the computer and the
interconnections..

Sure is a simple thing.. But that's another story..

To my immediate relief, there are 4 wires going from the circuit board to
the 4 pin connnector.. The colors don't exactly match those given for the
5
pin plug discribed on the web site. However Data IN is correct and there
is
Green wire that 'may' correspond to the Data OUT. Signal Gnd should be the
same for both but there just happens to be two more wires of different
colors left over, one of which I'm using for Data IN signal gnd. I didn't
have any test equipment on board and most likely will do a trial and error
once I install a 4 conductor cable on the OEM plug.. (problem there-- it's
molded and not intended to be opened. I'll have to cut away the mold
strain
relief and epoxy it back with the new wires.)

Steve, first print out this page:
http://www.shipmodul.com/en/connections.html

Based on your info, I would conclude the following: the two wires you
already successfully used to connect your GPS are Data IN+ and Data IN-. It
is an isolated differential input, as shown in fig.4, where your GPS
represents the 'instrument' and the Yeoman the 'multiplexer'.

The output of the Yeoman is probably singe-ended: one signal wire (green?)
and a ground wire. This will connect to your GPS as shown in fig.2, where
the Yeoman is the 'talker' and the GPS is the 'listener.
In your particular setup, you can safely connect the Data IN- to the ground
wire, to obtain a 'standard' 3 wire interface (In, Out, Ground).

Meindert