Re: Switching between multiple Volksloggers

[Mark Zivley]

Should work, best to test it first. Also, check to see if there is a
"ground" in the serial wiring diagram too. If so, you need to connect
them together as well, but that can be done permanently (not switched) I
would think.

Todd Pattist wrote:

> A friend has two Volksloggers, primary and secondary. The
> primary feeds data to his SN-10. The primary failed last
> weekend and he wants a way to switch the secondary to the
> SN-10 while in flight if it happens again.
>
> I suggested a simple double pole double throw switch to
> switch the TXD and RXD lines from the SN-10 between the
> primary and secondary VL's. Has anyone done this? Any
> problems?
>
> Thanks.
> Todd Pattist - "WH" Ventus C
> (Remove DONTSPAMME from address to email reply.)

[tango4]

I do the same with my twin colibris. Just switch the tx and RX lines. No
Problem

Ian


"Todd Pattist" > wrote in message
...
>A friend has two Volksloggers, primary and secondary. The
> primary feeds data to his SN-10. The primary failed last
> weekend and he wants a way to switch the secondary to the
> SN-10 while in flight if it happens again.
>
> I suggested a simple double pole double throw switch to
> switch the TXD and RXD lines from the SN-10 between the
> primary and secondary VL's. Has anyone done this? Any
> problems?
>
> Thanks.
> Todd Pattist - "WH" Ventus C
> (Remove DONTSPAMME from address to email reply.)

[Jim Vincent]

>> A friend has two Volksloggers, primary and secondary. The
>> primary feeds data to his SN-10. The primary failed last
>> weekend and he wants a way to switch the secondary to the
>> SN-10 while in flight if it happens again.

Diving into this perhaps a little late, but I wonder the value of doing this.
Is the SN-10 that much more reliable than a Volkslogger, your battery, or the
wiring switches? If you're found any of these individual components to
repeatedly fail, then I advocate replacing the component.

Looking at just two of the devices that contribute to the FMEA (Failure Modes
and Effects Analysis), let's assume the SN-10 and Volkslogger are equally
reliable. By only having one redundant, you're reduced the chance of failure
in half. BUT, assuming both are very reliable, on the order of 10,000 between
hours (reasonable), you'll increase the reliability from 99.999998 % to
99.999999 %.

Lastly, the switch that you need to switch between the two Volksloggers has its
own reliablity issue. That in inself may make the whole darn thing less
reliable.

I think the KISS approach is the best...one of each gizmos.

Batteries are a different story though. I have a spare one purely to power the
datalogger if the main one dies.

Jim Vincent
N483SZ

[Paul Remde]

Hi,

Several years ago a used a double pole-double throw switch to select between
my GPS-NAV and Garmin 90 for input to my L-NAV. That way I gained access to
the large Jepessen database when I was a long way from home. It worked
great.

However, the downside to using a switch is that RS-232 data lines are noisy
and it would be difficult to shield the switch well (putting foil around it
wont help). It may cause radio interference. Therefore, I don't really
recommend it.

Paul Remde
Cumulus Soaring, Inc.
http://www.cumulus-soaring.com

"tango4" > wrote in message
...
> I do the same with my twin colibris. Just switch the tx and RX lines. No
> Problem
>
> Ian
>
>
> "Todd Pattist" > wrote in message
> ...
> >A friend has two Volksloggers, primary and secondary. The
> > primary feeds data to his SN-10. The primary failed last
> > weekend and he wants a way to switch the secondary to the
> > SN-10 while in flight if it happens again.
> >
> > I suggested a simple double pole double throw switch to
> > switch the TXD and RXD lines from the SN-10 between the
> > primary and secondary VL's. Has anyone done this? Any
> > problems?
> >
> > Thanks.
> > Todd Pattist - "WH" Ventus C
> > (Remove DONTSPAMME from address to email reply.)
>
>

[tango4]

To do the job properley the swich should be mounted in a metal box ( sheet
ali or diecast ) and the box should be grounded. But I assumed that you'd do
it that way anyway!

Ian


"Todd Pattist" > wrote in message
...
> "Paul Remde" > wrote:
>
>>However, the downside to using a switch is that RS-232 data lines are
>>noisy
>>and it would be difficult to shield the switch well (putting foil around
>>it
>>wont help). It may cause radio interference. Therefore, I don't really
>>recommend it.
>
> Thanks Paul, that's the kind of info I was looking for.
> What kind of problems did you see? Were there problems on
> the RS-232 lines that caused data communication errors or
> are you referring to RFI and radio noise? I was going to
> give him some shielded cable for running to/from the switch,
> but I hoped it wasn't going to require putting the switch in
> a shielded box. I've got two GPS units that plug into
> sockets where the RS-232 RXD/TXD lines are exposed for a few
> inches, and I'm not seeing any problems. He was considering
> mounting one Volkslogger on its side so he could remove the
> cable and swap them, but I think that would cause more
> problems (with reception) than a simple switch.
> Todd Pattist - "WH" Ventus C
> (Remove DONTSPAMME from address to email reply.)

[Paul Remde]

Hi Todd,

It worked fine but I could hear it on the radio. Puting the switch in a
metal box and grounding the box should help but it seems silly to me since
the Volkslogger and SN-10 both can log the flight and are both very
reliable. Of course the SN-10 log can't be used for badges or records but
it could probably be used as a backup if the Volkslogger failed (which is
not likely if reliable 12V power is assured).

Paul Remde

"Todd Pattist" > wrote in message
...
> "Paul Remde" > wrote:
>
> >However, the downside to using a switch is that RS-232 data lines are
noisy
> >and it would be difficult to shield the switch well (putting foil around
it
> >wont help). It may cause radio interference. Therefore, I don't really
> >recommend it.
>
> Thanks Paul, that's the kind of info I was looking for.
> What kind of problems did you see? Were there problems on
> the RS-232 lines that caused data communication errors or
> are you referring to RFI and radio noise? I was going to
> give him some shielded cable for running to/from the switch,
> but I hoped it wasn't going to require putting the switch in
> a shielded box. I've got two GPS units that plug into
> sockets where the RS-232 RXD/TXD lines are exposed for a few
> inches, and I'm not seeing any problems. He was considering
> mounting one Volkslogger on its side so he could remove the
> cable and swap them, but I think that would cause more
> problems (with reception) than a simple switch.
> Todd Pattist - "WH" Ventus C
> (Remove DONTSPAMME from address to email reply.)