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Here are the connections you need to make to connect a USB
cradle to a serial cable to form a null-modem connection. In
a null-modem connection, the transmitted data from one device
is connected to the receive data pin of the other device, and
vice versa.
Inside the USB cradle, there are two connectors, CON1 and
CON2. CON1 is the external connector that mates with the port
on the bottom of the iPAQ handheld. CON2 is connected to the
USB cable. Because the USB data are on different pins from
the RS232 data, both a serial cable and a USB cable can be
connected at the same time.
Pin 1 of CON2 is indicated by a small triangle that points
to it.
Connections
| DB9 Female |
H3600 Cradle |
| Pin |
Name |
CON1 Pins |
CON2 Pin |
Name |
| 1 |
Data Carrier Detect (DCD) |
3 |
6 |
DTR |
| 2 |
Receive Data (RXD) |
7 |
4 |
TXD |
| 3 |
Transmitted Data (TXD) |
8 |
5 |
RXD |
| 4 |
Data Terminal Ready (DTR) |
9 |
7 |
DCD |
| 5, case |
GND |
4, 10, case |
9 |
GND |
| 6 |
Data Set Ready (DSR) |
3 |
1 |
|
| 7 |
Request to Send (RTS) |
5 |
2 |
CTS |
| 8 |
Clear to Send (CTS) |
1, 6 |
3 |
RTS |
| 9 |
Ring Indicator (RI) |
NC |
NC |
NC |
References
A description of RS232: http://www.rad.com/networks/1995/rs232/rs232.htm
Jim Pick's description of his serial cable adapter: http://www.handhelds.org/pipermail/handhelds/2000-July/000643.html
Acknowledgments
Thanks to Jim Pick and Scott Herndon for sending me the
CON2 pinout and correcting my CON1 pinout.
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