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Old June 13th 18, 05:26 PM posted to rec.aviation.soaring
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Default Feeding Two Devices from PowerFLARM

On Wednesday, June 13, 2018 at 11:55:15 AM UTC-4, wrote:
Yeah, I know this has been discussed. I've researched it. But I can't find this specific question answered.

I want to connect my PowerFLARM Portable to my LX FLARMView AND to my Kobo running TopHat. I don't think I need or can use a K6 Mux box: I'm not combining multiple inputs into a common output. It's the reverse: I want to use a single input to drive two outboard devices. I know there are other devices I can buy but I'm hoping it's really simple:

1. My PowerFLARM Portable has only one data port--an RJ45--vs. the two ports on the core--an RJ45 plus a DSub-9.
2. My FLARMView (rectangular model) has only one port--an RJ11--vs. the two such ports on the FLARMView 57 (round model)
3. I'm using an RJ45 cable to provide 12v to the PowerFLARM although I can also provide power via a separate dedicated power connector. I've also wired that cable to provide 5v to the Kobo and deliver the RX/TX wires to it from the PowerFLARM for GPS and FLARM target data.
4. Power and GPS/target data for the FLARMView are via a cable with an RJ45 connector on the PowerFLARM end and an RJ11 on the FLARMView end.
5. AFAIK, I'm not transmitting anything to the PowerFLARM from the Kobo/TopHat: i.e., no flight declarations, no MacCready settings. The same thing is true, I think, for the FLARMView: no downloads. To the best of my knowledge, all data moves in one direction only: from the PowerFLARM to the FLARMView and to the Kobo/TopHat (for GPS location and targets). Each of these set ups works fine: i.e., PowerFLARM connected to the Kobo/Top Hat and PowerFLARM connected to the FLARMView. But I have to pick one or the other now. I'd like to drive both devices at the same time.

So under this simplified case, can I simply connect the RJ45 ends of cables from the FLARMView and the Kobo into a dual-port adaptor and plug that into the back of the PowerFLARM, while providing power to the PowerFLARM via the separate connection?

Why, you ask? Well, I'm seeing some but not all of the FLARM target info displayed in Top Hat--the problem I posted about last year. So until I figure out a way to solve that problem, I'd like to have the small FLARMView display up at the same time as Top Hat is running on the Kobo.

Chip Bearden


Are you SURE that the FLARMview does not connect a data-out wire to the data-in wire of the FLARM unit? If it uses a standard bi-directional serial communications chip, there may be a voltage on that wire - even if no data is being sent. Same with the Kobo. You can modify your cable so as to ensure the data-out wire from the Kobo is not connected at all, that would eliminate the possibility of the Kobo wrestling with the FLARMview over the voltage level in that wire, possibly damaging the serial chips in either unit.

Other than that, the only issue is how much of a load both devices' data-in ports in parallel pose to the data-out wire of the FLARM, that will probably work fine even if it's officially verboten.