How do I wire my GPS to multiple devices?
I have a Garmin GPS 12 (handheld) mounted on the instrument panel. I use the
Garmin PC/DC cable to get 12 volt power from my utility lighter, and to
connect to a serial connector.
I have a Furuno 1622 radar with a Furuno NMEA cable, to which I added a
serial cable to connect to the Garmin PC cable. That works great: lat/long,
waypoints, course and speed displayed on the radar.
I'm replacing my VHF radio with one that has DSC and NMEA input. The NMEA
input plug looks like that on a stereo headset cord.
How do I get the GPS wired to that and the radar serial connector?

You can easily make a Tee type of cable that has multiple NEMA outputs.
Generally speaking you are not supposed to do this but we have had
excellent results running 2 devices requiring NEMA data. Most serial
devices do not pull enough current to drop the 5 volt signal signficantly.

The manufacturer of your radio should be able to tell you which part of the
stereo plug is ground and which part is NEMA data in.

Lisa
www.ultimatepassage.com

William G. Andersen wrote:

How do I wire my GPS to multiple devices?
I have a Garmin GPS 12 (handheld) mounted on the instrument panel. I use
the Garmin PC/DC cable to get 12 volt power from my utility lighter, and
to connect to a serial connector.
I have a Furuno 1622 radar with a Furuno NMEA cable, to which I added a
serial cable to connect to the Garmin PC cable. That works great:
lat/long, waypoints, course and speed displayed on the radar.
I'm replacing my VHF radio with one that has DSC and NMEA input. The NMEA
input plug looks like that on a stereo headset cord.
How do I get the GPS wired to that and the radar serial connector?

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

"Lisa Collins" wrote in message
...
You can easily make a Tee type of cable that has multiple NEMA outputs.
Generally speaking you are not supposed to do this but we have had
excellent results running 2 devices requiring NEMA data. Most serial
devices do not pull enough current to drop the 5 volt signal signficantly.

The manufacturer of your radio should be able to tell you which part of
the
stereo plug is ground and which part is NEMA data in.

Lisa
www.ultimatepassage.com

William G. Andersen wrote:

How do I wire my GPS to multiple devices?
I have a Garmin GPS 12 (handheld) mounted on the instrument panel. I use
the Garmin PC/DC cable to get 12 volt power from my utility lighter, and
to connect to a serial connector.
I have a Furuno 1622 radar with a Furuno NMEA cable, to which I added a
serial cable to connect to the Garmin PC cable. That works great:
lat/long, waypoints, course and speed displayed on the radar.
I'm replacing my VHF radio with one that has DSC and NMEA input. The
NMEA
input plug looks like that on a stereo headset cord.
How do I get the GPS wired to that and the radar serial connector?

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

"Rodney Myrvaagnes" wrote in message
...
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

Two loads of the type described will definitely not create a problem. I
concur with your statement that a MUX is superfluous.

Not sure what you consider inexpensive re mux's, but there's a Kiwi company
called Brookstone which markets several flavors, the cheapest of which goes
for $149. I have one, and it works fine.

Max Lynn
First 40.7
Tranquility

"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

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.

Steve,

Actually a mulxtiplexer is designed to compress multiple serial lines into a
single physical proprietary formatted data stream. This single line may be
connected directly to a modem, frame relay or even tunneled on a TCP/IP
connection to a second multiplex whose job is to split the connection back
into distinct serial lines. A typical 4 port multiplexer system would like
like this:

+----------+ +----------+
device 1--| | | |--device1
| | | |
device 2--| |wire/phone | |--device2
| Mux |-------------| Mux |
device 3--| | | |--device3
| | | |
device 4--| | | |--device4
+----------+ +----------+

The point of using a multiplexer is to maintain separate physical
connections between the local and remote sides while only using a single
resource (typically a phone line). Each device maintains its independence
i.e. device 1 on the local side can only talk to device 1 on the remote
side, etc. This is exactly Mr Anderson doesn't want to do.

In fact, in Mr. Anderson's orignal post, he explicitly states that he has a
single broadcaster and multiple receivers. There can be no collisons. The
only question is whether the sum of the current draws of the the receivers
is enough of a current sink to pull down the 5 volt transmitter source.


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

"Lisa Collins" wrote in message
...
You can easily make a Tee type of cable that has multiple NEMA outputs.
Generally speaking you are not supposed to do this but we have had
excellent results running 2 devices requiring NEMA data. Most serial
devices do not pull enough current to drop the 5 volt signal
signficantly.

The manufacturer of your radio should be able to tell you which part of
the
stereo plug is ground and which part is NEMA data in.

Lisa
www.ultimatepassage.com

William G. Andersen wrote:

How do I wire my GPS to multiple devices?
I have a Garmin GPS 12 (handheld) mounted on the instrument panel. I
use the Garmin PC/DC cable to get 12 volt power from my utility
lighter, and to connect to a serial connector.
I have a Furuno 1622 radar with a Furuno NMEA cable, to which I added a
serial cable to connect to the Garmin PC cable. That works great:
lat/long, waypoints, course and speed displayed on the radar.
I'm replacing my VHF radio with one that has DSC and NMEA input. The
NMEA
input plug looks like that on a stereo headset cord.
How do I get the GPS wired to that and the radar serial connector?