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Garmin GTR 200 Standby freq with two GPS

gvgoff99

Well Known Member
Is GTR 200 Stndby freq flip/flop from two GPS possible?

Garmin GTR 200 Standby

I have tandem seating and a GPS 660 mounted in the rear and a GPS 796 mounted up front. The only radio is a GTR 200. I plan to use the RS232 (out) from the 660 and use the touch screen to input frequencies to the standby freq via the RS232 in (pin 24) on the GTR 200 for the rear seat person.
The GPS 796 has the same capability for inserting into standby. It would be useful to have the same standby freq change capability from the 796 but there is only one RS232 In on the GTR 200.

1. Would it be possible to use ?On-Off-On? toggle switch to change which GPS is sending standby freq info to the GTR 200?
2. If it were feasible, would it be a problem to switch between the two GPS while all the electronics are turned on during flight? (The 232 signal interruption from one GPS to another would not "confuse" the GTR 200?)

Thanks, George
 
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Garmin GTR 200 Standby

I have tandem seating and a GPS 660 mounted in the rear and a GPS 796 mounted up front. The only radio is a GTR 200. I plan to use the RS232 (out) from the 660 and use the touch screen to input frequencies to the standby freq via the RS232 in (pin 24) on the GTR 200 for the rear seat person.
The GPS 796 has the same capability for inserting into standby. It would be useful to have the same standby freq change capability from the 796 but there is only one RS232 In on the GTR 200.

1. Would it be possible to use ?On-Off-On? toggle switch to change which GPS is sending standby freq info to the GTR 200?
2. If it were feasible, would it be a problem to switch between the two GPS while all the electronics are turned on during flight? (The 232 signal interruption from one GPS to another would not "confuse" the GTR 200?)

Thanks, George

Hello George,

We haven't tested this, but what you suggest should work since it never ties the Aera 660 and Aera 796 RS-232 transmitters together.

Please contact us directly by phone or email if you have additional questions.

Thanks,
Steve
 
With some diodes to ensure the two GPS' don't try to send to each other, you could possibly wire it up without the switch. The question would be what happens to the GTR if two GPS' try to send a frequency at the same time.

Don't forget to wire the frequency swap button to the back seat as well... :)
 
With some diodes to ensure the two GPS' don't try to send to each other, you could possibly wire it up without the switch.

Sorry, but that wouldn't work. Each Aera is constantly transmitting NMEA and VHF data including frequencies and frequency identifiers for hundreds of nearby airports and the airports in the flight plan.

This allows you to press and rotate the knobs on the GTR 200 and always have an airport frequency list for the nearest airports without having to look it up.

The infrequent command to send a single selected standby frequency to the GTR 200 is a negligible amount of the total communication which is occurring.

Tying two Aera transmitters together with diodes would create mayhem with both of them constantly stepping on each other. It is likely that nothing would work if you did this.

Steve
 
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