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- Visor & Deluxe (http://discussion.visorcentral.com/vcforum/forumdisplay.php?forumid=1)
-- Mark/Space Hotsync and modem cables (http://discussion.visorcentral.com/vcforum/showthread.php?threadid=16407)

Mark/Space Hotsync and modem cables

Has anyone taken apart or acquired the schematics for the conversion circuit in the Mark/Space datacord DCH-M9? I'm curious why this cable can't double as a hotsync cable. Power for the conversion circuit(I think) is taken from pin 3 of the Visor. This pin is normally the HotSync interrupt and can only supply less than 1mA of current without confusing the Visor.

Hotsync version of DCH-M9

You know, I had tried that. Conceptually it's simple - a DCH-M9 is Visor powered, but to connect it to a PC serial port is pretty easy if you just swap the transmit and receive, etc. - pretty much the same a putting a null modem adapter on the end of it.

However, when you go to try to hotsync, the PC never "recognizes" the Visor. My opinion is that the PC is actually checking one of the hardware handshake lines (say RTS or DTR), and since a DCH-M9 with a swapped Rx and Tx is not quite the same as the connection on a serial cradle (which loops back some of these and uses them to power the electronics), the interface does not respond the same and the hotsync does not proceed. ("ben's speculative explanation")