Thanks, it's interesting but doesn't provide and details on wiring.


"Tomek Niedba³a" wrote in message
...

U¿ytkownik "William G. Andersen" napisa³ w wiadomo¶ci
news:8UVTc.8062$yh.5539@fed1read05...
How do I wire my GPS to multiple devices?

I found it very useful

http://www.cactusnav.com/brochures_guides.htm

http://www.cactusnav.com/BrochureRac...EA%20Guide.pdf

Greetings from Poland

Tomek

"Steve Lusardi" wrote in message
...
Lisa,
NMEA interfaces are slow and bit serial (EIA RS-232). The protocol is very
basic and there is no provision for either addressing or data collisions.
As
you stated, your solution is incorrect, the device to use is called a
statmux or statistical multiplexor in general.

You don't need a multiplexer to feed one NMEA stream into more than one
device. You only need one when multiple NMEA streams, like from a GPS *and*
some nav instruments are to be fed into one listener, like a computer or an
autpilot.

The NMEA standard specifically states that one talker (a GPS) should be able
to drive up to four listeners *simultaneously*. So even according to the
official spec it is perfectly ok to connect the output of a GPS to the input
of a radar AND a VHF.

Meindert
www.shipmodul.com

"Rodney Myrvaagnes" wrote in message
...
On Mon, 16 Aug 2004 19:50:12 +0200, "Steve Lusardi"
wrote:

But, since you mention it, where are there inexpensive muxes? I had
one once until it was hit by lightning, but it was very expensive at
the time.

Well, depends on what you call inexpensive. The world-famous Noland
multiplexer is about $200. Ours are a bit more expensive (starting from
around $250) but have more functions and comply with the EMC rules ;-)

Meindert

"William G. Andersen" wrote in message
news:sfgUc.9864$yh.8177@fed1read05...
Kelton,
You seem to have done what I want to do. How did you physically connect
one
Garmin to four devices? What parts/connections did you buy?

Just splice the TX or OUT wire from the GPS to the input from the VHF and
the radar. Do the same for the signal return or ground wire.

Meindert

William G. Andersen wrote:

Kelton,
You seem to have done what I want to do. How did you physically connect one
Garmin to four devices? What parts/connections did you buy?


If you're asking about the mechanics of doing it, a typical installation
would be with a 10 post screw terminal strip. For 4 additional devices,
bring the two NMEA (Data In and Out) wires to the first two terminals on
the strip, then make short jumpers to bring the data across to create
the next four pairs. Use ring or spade terminals
(http://www.installdr.com/TechDocs/999402.pdf)for the wires in and on
the jumpers.

If the screws were numbered 1 - 10 left to right, the NMEA data would
come onto the terminal strip at 1 and 2. Terminal 1 would be jumpered
to 3, 5 7, and 9. Terminal 2 would be jumpered to 4, 6, 8, and 10.

In the below, if the in pair were pins 1 and 2 the additional pairs
would be 3 and 4, 5 and 6, 7 and 8, 9 and 10.

1 2 3 4 5 6 7 8 9 10
| + + | + + | + + | + + | + + |
| | | | | | | | | |
| + + | + + | + + | + + | + + |

Some people will argue about doing it but my preference is to strip and
tin all wires before crimping the terminals on as it gives one solid
bundle for the crimp to act on.

For this job a terminal strip using #6 or #8 screws would be about
right, buy crimp on terminals appropriately sized to the wires. The
22-18 guage (red) ones would typically be right for this. If some of
the wires are smaller guage (26 is not uncommon) strip bare a double
length of wire, fold it back on itself to double the size for crimping,
and then tin that.

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jacker at midmaine dot com

William,
I have a mount for my GPS in the steering pedestal. I mounted a four
terminal block inside the pedestal and wired +battery and -battery to
the block.
1. The four wire Garmin cable is connected to the block ( +, -, data in,
data out ).
2. A two wire cable is connected to the block ( -, data out )and routed
into the instrument pod and connected to the autopilot NMEA - and +
terminals.
3. From the terminal block I ran a four conductor cable down to my
navstation area. I installed another four terminal block there and
connected the cable to the block.
4. The VHF radio acessory cable GPS data in and - are connected to the
block ( Garmin data out and - ).
5. The Pactor IIe cable to the HF radio is a "Y" cable (available from
Faralon Electronics). The "Y" had a DB9 connector. I made a DB9 pigtail
cable and connected the data in and - to the block ( Garmin data out and
- ).
6. I made a another DB9 pigtail to connect to the computer. Data in an -
to Garmin data out and -.
7. I also connected second Garmin data cable to the block so that I
could remove the GPS from the pedestal and use it at the navstation
(usefull when planning routes and uploading them to the GPS).

Kelton
s/v Isle Escape



William G. Andersen wrote:

Kelton,
You seem to have done what I want to do. How did you physically connect one
Garmin to four devices? What parts/connections did you buy?

"Kelton Joyner" wrote in message
...

The manual with my Garmin GPS48 states that it will drive 4 listeners. I
have it connected to the autopilot NMEA input, VHF DSC input, computer
input, and Pactor IIe input. Works OK.All devices get and process the
GPS NMEA sentences.
Kelton
s/v Isle Escape

Rodney Myrvaagnes wrote:

On Mon, 16 Aug 2004 19:50:12 +0200, "Steve Lusardi"
wrote:



Lisa,
NMEA interfaces are slow and bit serial (EIA RS-232). The protocol is

very

basic and there is no provision for either addressing or data

collisions. As

you stated, your solution is incorrect, the device to use is called a
statmux or statistical multiplexor in general. Specifically, there are
multiplexors available for this purpose that prevent data collisions and
allow orderly sentence broadcast. Contact a qualified nav equipment

dealer

for further info. These devices are inexpensive and available.
Steve


Since Lisa was only proposing a single "talker" a mux is superfluous.
No collisions could occur. The only issue is whether the two loads
would reduce the signal too much.

But, since you mention it, where are there inexpensive muxes? I had
one once until it was hit by lightning, but it was very expensive at
the time.

Thanks




Rodney Myrvaagnes NYC

J36 Gjo/a


"Wanting to meet a writer because you like his work is like wanting to

meet a duck because you like pate."

Margaret Atwood

On Mon, 16 Aug 2004 22:00:42 -0700, "William G. Andersen"
wrote:

Thanks, Lisa: guess I'll go to a Radio Shack and see what they have to make
a Tee type of cable. My few previous experiences with the local store were
frustrating because they were just sales clerks and didn't understand what I
wanted to do, so they couldn't offer any help.

See http://vancouver-webpages.com/peter/seaspray_nmea.pdf for the NMEA
wiring on my boat. I can have either of two GPS receivers feed the
computer, and either the selected GPS or the computer feeds the
autopilot. Since I made that drawing, I've added a radar which is
connected in parallel with the computer RX data.

I used a screw terminal strip to make the connections, but you could
simply splice all the wires together, without using any additional
hardware.

--
Peter Bennett VE7CEI
email: peterbb4 (at) interchange.ubc.ca
GPS and NMEA info and programs: http://vancouver-webpages.com/peter/index.html
Newsgroup new user info: http://vancouver-webpages.com/nnq

On Tue, 17 Aug 2004 09:06:49 -0400, Jack Erbes
wrote:

Some people will argue about doing it but my preference is to strip and
tin all wires before crimping the terminals on as it gives one solid
bundle for the crimp to act on.

That's not a smart thing to do. If the connection ever overheats for
some reason, the solder could heat to the point of melting, and allow
the wire to slip right out of the crimp connection! If you want to
solder, crimp first, then apply solder. The other way around can be
dangerous.

--
BRENT - The Usenet typo king.

"Brent Geery" wrote in message
...
On Tue, 17 Aug 2004 09:06:49 -0400, Jack Erbes
wrote:

Some people will argue about doing it but my preference is to strip and
tin all wires before crimping the terminals on as it gives one solid
bundle for the crimp to act on.

That's not a smart thing to do. If the connection ever overheats for
some reason,

It doesn't even have to get overheated. Solder flows, also in cold
condition. You can test that yourself: tin the end of a stranded wire, put
it into a screwterminal and tighten it. After a week or so, check if the
screw is still tight: it isn't.

Crimp first. Then apply some solder if you like.

Meindert

Well, depends on what you call inexpensive. The world-famous Noland
multiplexer is about $200. Ours are a bit more expensive (starting from
around $250) but have more functions and comply with the EMC rules ;-)

Meindert


Keep away from the Brookhouse mux's from New Zealand. I had one which never
worked properly and their tech support is lousy.