At 07:30 PM 5/10/2012, you wrote:
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Glider tools have a cheap cable adapter Euro$43
http://www.glidertools.com/products/converter-rs232-to-usb-for-pna-with-swit
ching-power-supply-5v/
http://forum.xcsoar.org/viewtopic.php?f=3&t=342&p=1293&hilit=glidertools#p1293by
max ยป Tue Feb 14, 2012 2:05 am Nikitovich
wrote:http://www.glidertools.com/products/converter-rs232-to-usb-for-pna-with-switching-power-supply-5v/Does
anybody know if it's is working properly with an
android device.No. This is a proprietary adapter
for a few PNA models that have a "real" (hidden)
RS-232 port on the USB connector.
You are right Bernie. I have one of those devices
and it puts either ground or 5v on one pin of
the 5 pin mini USB connector to tell the PNA to
switch the port to RS232 instead of USB. USB
actually only needs 4 pins, power, ground and A
and B data lines. It is actually a differential
RS422 in hardware terms. One line goes high while
the other goes low. RS 232 is normally up to +/-
15 volts but only one line changes state on an
input or output and is referenced to ground. On
the PNA though the "RS232"is really inverted
logic level and on the V2 and similar generic
devices goes from 3.3 volts to ground. Put a real
RS232 on that port and you'll likely blow up the
device. You need a buffer, inverter and level
shifter. Not difficult as chips are available to
do this. the glider tools power supply supplies 5
volts and does the buffering of the data lines.
Mike
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