[aprssig] D710 Greenlight Labs GPS and AVMAP?

Brad Burleson bradb667 at gmail.com
Fri Jun 22 00:19:55 CDT 2012

On Thu, Jun 21, 2012 at 5:50 PM, Stephen H. Smith <wa8lmf2 at aol.com> wrote:
> But again, whether you use a 'Y"-cable of some sort, or the Greenlight's
> pass-through, you would be wiring two  RS-232 OUTPUTS (The AVmap's NMEA
> output and the Greenlights NMEA output) IN PARALLEL.
> Even if there is some option to turn off the AVmaps output NMEA stream so
> it's receive-only for data sent FROM the Kenwood, you will have the output
> side of the AVmap serial port resting at  the negative 5-8 volts of a
>  quiescent RS-232 circuit (or possibly at 0 volts if it uses 0/5 "half-232"
> inverted TTL output), in parallel with the active output of the Greenlight.

Good point.  This problem would limit the usefullness of the pass-thru
itself, and as a result I'd think that Greenlight wouldn't pass data
in both directions - instead only "outbound" to the pass-thru.

And if you take a look at
http://www.greenlightlabs.com/gps-710/PC_Interface.htm you'll see that
in fact the "pass-thru" ISN'T bi-directional at all.  Of the 3 wires
on the pass-thru, you get ground, data from radio and data from GPS.

So I _suspect_ with the correct cable, this should just work.

Or did I miss something else?



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