Re: Gizmo hardware problems

If I understand your problem, device A will talk to B, B will talk to C, 
but A and C won't talk.

If so, my solution to a similar problem was to check the voltages used for 
signaling between serial ports on the respective computers. I learned that 
my "A and C" combo was a case of one machine only talking at 5v and the 
other would only recognize a higher voltage in the positive-going 
direction. 

I wound up fixing it by stealing +12 volts from a USB port and using it to  
feed a pull-up circuit for that data line. I can dig out the schematic 
for the fix if you want, but the idea is to find out the signal levels 
that the equipment you have really needs for reliable communication.
An oscilloscope is the tool of choice here.

Good luck,
Dave McCue