serial port comm with Video device

Hi all

I've built a basic circuit to communicate from a Sony Camcorder to my PC, using the serial port and a small circuit (MAX233A chip with one capacitor, to invert/amplify the 5V signal from LANC) to allow the data exchange.

since sony uses a standard very close to the RS232 protocol, I was able to read some data and to confirm that I all the wiring i basically ok.

Only problem is that the Sony protocol have all the data going thru one pin
(the LANC pin) and I need to plug both the RX and TX line on it if I want to send/receive.
only with the RX wire i'm fine, i can read data sent by the camera at full 9600baud speed with a Delphi program.
As soon as I add the TX wire the data stop to go...

and that's were i'm stuck. :roll:

my circuit is similar to what's on this page:
http://www.compsys1.com/workbench/On_top_of_the_Bench/Max233_Adapter/max233_adapter.html

so i'm there, and completely lost because my university diploma is saying : mech engineer :?:

any electronic guru could point out the problem i'm having right now?


Thanks very much!

Dom