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HP Forum Archive 13
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|Wanted: Hp Xpander connectivity cable schematic|
Message #1 Posted by Sean McNamee on 10 Aug 2003, 8:02 p.m.
Hi all -
Bought an Xpander without connnectivity parts (cable or CD).
I'd like to u/l some WinCE software to it - can someone post the cable schematic? Or perhaps point me to somehwere this info might be on the web already?
Also, what software would I need on the PC side? I assume that something can be substituted for whatever came with the XPander originally....
Message #2 Posted by Mike on 10 Aug 2003, 8:52 p.m.,
in response to message #1 by Sean McNamee
I believe the cable is special and may contain electronics in the 9 pin plug end.
There is a warning in the manual that it's a special designed 9 pin plug for HP. One end is a 9 pin female. The other end is a phone plug.
I buzzed the cable and only one pin makes continuity to the 9 pin connector (see photo). I checked both polarities, for diodes, and still no continuity. That leads me to believe there is electronics in the 9 pin end.
Edited: 10 Aug 2003, 8:53 p.m.
|Re: Special Cable|
Message #3 Posted by Colin on 10 Aug 2003, 11:10 p.m.,
in response to message #2 by Mike
There is an RS232 level converter in the housing of the DB9 connector. 3V logic at the Xpander connection. Only RX, TX and GND are present. Don't ask me which one because I just cannot remember.
|Re: Special Cable - RS232 level converters|
Message #4 Posted by Bill Wiese on 11 Aug 2003, 12:56 p.m.,
in response to message #3 by Colin
Yep, the cable has some level RS232<==>5V logic level converters in it.
You can do this with a couple of transistors & resistors & caps or do it right w/a chip.
A typical & common chip used for this task is the Maxim MAX232. I believe there is a successor called the MAX2232. Other variations (...233, etc.) also exist.
These are 'low power' chips.
The cable's electronics is likely powered from the RS232 connector. Sounds like it's just using TxD, RxD and Gnd (pins 1,2,3,7, IIRC, on a DB25 - dunno about DB9) and picking up power from another signal line like CTS, DTR, etc.... The PC application software may have to switch one of these control lines from default state to power up the electronics in the cable head.
San Jose, CA
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