Pinout Palm III Pigtail:
 
Count pin numbers from front-connector left to right (like cradle front-view - Pin1/DTR left), looking at the back of your Palm device from right to left. Double check!!

 
Pin # PalmPilot/Palm III Signal Colour
1 DTR (Out) yellow
2 Vcc (Out) 3.3VDC via 330 ohms - not battery voltage like on PalmV! white
3 ReceiveData (In) brown
4 RTS (Out) blue
5 TransmitData (Out) black
6 CTS (In) green
7 GPI1 (In) -> HotSync Button purple
8 GPI2 (In) -> Modem HotSync grey
9 Unused no contact
10 SignalGround red!
 

Cable screen is NOT connected to pin 10/ signal ground/red, but to the metal fixing clamp of the palm connector.
If you make your own hotsync or modem cables, connect the screen to the metal frame of the DB9 or DB25 connector, NOT to the signal ground pin of the RS232 Interface!

Pin 9 is not connected, however, some people use this pin for feeding in external power supply for the Palm devices. If you want to do that, the best way is to open the Palm connector and solder the red wire/pin 10 to pin 9, and connect the cable screen to pin 10 instead as a ground line.
If you don't use pin7 or pin8, you can also use those.

Palm V Pigtail has same signals for RS232, but colours are different, plus there are two pins handled differently for charging the internal LiION cell.

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Don't blame me if you blow your Palm!

© Carsten Kurz, August 1999