At 06:11 19 July 2008, Peter Wyld wrote:
At 21:29 18 July 2008, Doug Hoffman wrote:
Shaun McLaughlin wrote:
I have a problem with my GPSNAV (model 20 I believe, with the
external
antenna). The GPSNAV output to the screen works fine, directs me to
the
waypoints etc. This shows that the GPS engine is working.

However, the output to the PDA via the serial port, and the Datacom
output
to the L-Nav seems to be doing nothing. The cables are definitely OK.

I am unable to find a .cai trace on the logger after a flight, output
to
the PDA is hugely intermittant- it works for a few seconds at most
over
a
whole flight. The L-Nav reads GPS (Wait).

Has anyone else experienced similar problems?

I have has *exactly* the same problem with my LNAV-GPS20 setup. I
finally gave up and bought a Garmin Vista GPS to run my PDA. I would
be

very interested in any solutions to this problem. I know the GPS20 is
internally working fine because on its readout all information is
correct. I just can't get a signal from the GPS20 DB9 output to run
my
PDA.

-Doug


Shouldn't you be looking for the NMEA datastream on the 6way
'telephone' socket, not the DB9 serial port?

If you have the GPS20 connected to the LNAV via this port, you can take
a
tap from it to run the PDA.


I seem to remember from configuring my Cambridge GPS model 25 that the
NMEA data on the 6 way port is a subset of the NMEA data available via the
DB9 connector. If you examine the data stream output, it is missing
certain important NMEA sentences inc GPS altitude.(which is not required
by a LNAV, but is required by PDA programs)
The DB9 connector is the correct one to use when connecting to a PDA, but
the PDA program has to first send a "NMEA" command to the GPS to send
out data on this port. This occurs when when PDA software eg Seeyou mobile
starts up.
The DB9 connector is also required if you wish to upload tasks and
download logs.

With regards to your NMEA problems from the Cambridge, does this occur
without a PDA connected ?

Rgds
Ian