olivier101
Member

Registered: Feb 2001
Location: Luxembourg
Posts: 68 |
OK, since both the T28 and Visor serial interfaces operate at TTL levels (0/+5V), you do not need to go through some circuitry to bring these levels to RS232 levels.
Besides, this kind of circuitry which is included in the phone-to-PC cable or Visor serial cable/cradle draws power from the PC, so a connection like the following probably wouldn't work:
T28 <-> T28 RS232 adapter <-> null-modem adapter <-> Visor serial cable or cradle <-> Visor
What you need is a T28 bottom connector, a Visor connector, and some shielded cable with 3 wires. Get the connectors pinout, then just connect Rx to Tx, Tx to Rx, and ground to ground.
The biggest problem is getting the connectors, so you'll probably have to buy the serial cables anyway, just to get the connectors...
If you're unsure how to build the cable, have it done by someone. You may want to check with this guy who makes custom cables: http://www.cables4pdas.com
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