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

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

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

"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

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

Meindert Sprang wrote:

"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.


Like I said, some people will argue about it... :)

If the wires are hot enough to melt solder the insulation is also
probably starting to melt away and you have more problems than a simple
loose connection. Also, in a marine environment, a tinned end will
arguably oxidize less and corrode less over time than an untinned end.

Look at the untinned copper wire connections on terminal strips in a 50
year old boat if you don't believe me. Soldering can be a bad choice
(like if acid core solder is used) but it has some good points too.

And I described crimping a spade lug onto the tinned end and putting
that under the terminal screw, not putting the tinned strands under the
screw.

Some crimpers leave a flattened clamping area that will let untinned
wires shift around in it and then the crimped spade terminal can lose
its grip. I was talking about the average hardware store terminal, put
on with the average hardware store crimping tool, by a non-professional
doing his own work. I know a little about four point crimpers, full
contact compression or swaged crimps, and other ways to get both good
contact and high pull strengths but the terminals and tools are not
found in the average hardware store.

As far as trying to solder on terminal lugs that have already been
crimped on? That sounds nothing short of bizarre to me. To each their
own I guess.

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

Thank you, Kelton.
That's just the detailed information I was looking for! I guess this will
have to be one of my next projects - I'm getting tired of seeing all those
wires under the instrument panel. This should let me get the wires organized
so that I can have a neat installation and eliminate or stow the excess
wires.

Bill
"Kelton Joyner" wrote in message
...
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