NMEA and SeaTalk on same network
 

I have on board devices from Raymarine, working under SeaTalk protocol
and also a Raystar plotter using a NMEA GPS signal. On the boat there
is a NMEA to SeaTalk Bridge Unit, so exists a "mixing" of all the
data. Upto now : no problems !

My question:
I would like to add a second GPS (Raystar 125) connecting its SeaTalk
output signal to the SeaTalk network. This would be meant to be a
reserve in case of failure of the first one. May I leave it in
operation, having GPS data coming from two devices, or it's better to
keep it off and disconnected while the first one is in operation ?

In theory there should not exist collisions on the talker side, but
what about same data flowing on the same network ?

Appreciated your comments

Manlio

NMEA and SeaTalk on same network
 

Manlio wrote in news:kgoks3lt7mrm6s0cavklpprrs2t1sf2kro@
4ax.com:

I have on board devices from Raymarine, working under SeaTalk protocol
and also a Raystar plotter using a NMEA GPS signal. On the boat there
is a NMEA to SeaTalk Bridge Unit, so exists a "mixing" of all the
data. Upto now : no problems !

My question:
I would like to add a second GPS (Raystar 125) connecting its SeaTalk
output signal to the SeaTalk network. This would be meant to be a
reserve in case of failure of the first one. May I leave it in
operation, having GPS data coming from two devices, or it's better to
keep it off and disconnected while the first one is in operation ?

In theory there should not exist collisions on the talker side, but
what about same data flowing on the same network ?

Appreciated your comments

Manlio

My experience with trying to solve the same issue was that it was better to
have one as a reserve (hot plug-in) instead of having them both active. I
had 1 NMEA which was connected to an NMEA input on the course computer and
1 SeaTalk GPS and there were issues that I can't really remember at this
point.

However, the solution that I finally came down to was unplugging the
SeaTalk GPS and having it as a stand-by unit. I seem to remember that it
had more to do with the fail-over not working well on the chartplotter (a
RayMarine C80 and a NorthStar 6100i (for hardware and software
redundancy)).

-- Geoff
www.GeoffSchultz.org

NMEA and SeaTalk on same network
 

Followup to msg on Sun, 02 Mar 2008 06:11:56 -0600, Geoff Schultz
:
(Original msg on bottom)

Thanks Geoff,
you contribution is much appreciated. It's about what I was
forecasting to happen.
Cheers
Manlio



Manlio wrote in news:kgoks3lt7mrm6s0cavklpprrs2t1sf2kro@
4ax.com:

I have on board devices from Raymarine, working under SeaTalk protocol
and also a Raystar plotter using a NMEA GPS signal. On the boat there
is a NMEA to SeaTalk Bridge Unit, so exists a "mixing" of all the
data. Upto now : no problems !

My question:
I would like to add a second GPS (Raystar 125) connecting its SeaTalk
output signal to the SeaTalk network. This would be meant to be a
reserve in case of failure of the first one. May I leave it in
operation, having GPS data coming from two devices, or it's better to
keep it off and disconnected while the first one is in operation ?

In theory there should not exist collisions on the talker side, but
what about same data flowing on the same network ?

Appreciated your comments

Manlio

My experience with trying to solve the same issue was that it was better to
have one as a reserve (hot plug-in) instead of having them both active. I
had 1 NMEA which was connected to an NMEA input on the course computer and
1 SeaTalk GPS and there were issues that I can't really remember at this
point.

However, the solution that I finally came down to was unplugging the
SeaTalk GPS and having it as a stand-by unit. I seem to remember that it
had more to do with the fail-over not working well on the chartplotter (a
RayMarine C80 and a NorthStar 6100i (for hardware and software
redundancy)).

-- Geoff
www.GeoffSchultz.org

NMEA and SeaTalk on same network
 

I seem to remember that it
had more to do with the fail-over not working well on the chartplotter

Yes, I've seem the same sort of thing. More than the chartplotter will
probably 'favor' the SeaTalk-connected one first and the the NMEA unit. The
only trouble with keeping one as a spare is corrosion of the open
connections. You don't want to just unplug it and leave the ends hanging.
Be sure to cap them.

NMEA and SeaTalk on same network
 

Manlio wrote in news:kgoks3lt7mrm6s0cavklpprrs2t1sf2kro@
4ax.com:

I would like to add a second GPS (Raystar 125) connecting its SeaTalk
output signal to the SeaTalk network. This would be meant to be a
reserve in case of failure of the first one. May I leave it in
operation, having GPS data coming from two devices, or it's better to
keep it off and disconnected while the first one is in operation ?



You must NEVER have TWO GPS units talking to the network at the same time.
They will NEVER put out the same data. The results are that every plotter
on the boat goes crazy with the conflicting data streams, your position
jumping from A to B to A to B all the time.

If you want to have a backup GPS, that's fine as long as only ONE of them
are talking to the system at a time. We have two, one Raystar 120 and one
Garmin. There is a simple toggle switch to select which one of them is the
talker so noone can set both of them talking simultaneously.

NMEA and SeaTalk on same network
 

Followup to msg on Sun, 02 Mar 2008 18:08:06 +0000, Larry
:
(Original msg on bottom)

Thanks to all of you. You have just confirmed all my presumed doubts
making them certainty.
BTW it's too much important to have a "spare" GPS ( I will keep it off
in the right way) as, despite my age (!!) I will have some trouble to
unbury my old sextant !! :-))

Manlio



Manlio wrote in news:kgoks3lt7mrm6s0cavklpprrs2t1sf2kro@
4ax.com:

I would like to add a second GPS (Raystar 125) connecting its SeaTalk
output signal to the SeaTalk network. This would be meant to be a
reserve in case of failure of the first one. May I leave it in
operation, having GPS data coming from two devices, or it's better to
keep it off and disconnected while the first one is in operation ?



You must NEVER have TWO GPS units talking to the network at the same time.
They will NEVER put out the same data. The results are that every plotter
on the boat goes crazy with the conflicting data streams, your position
jumping from A to B to A to B all the time.

If you want to have a backup GPS, that's fine as long as only ONE of them
are talking to the system at a time. We have two, one Raystar 120 and one
Garmin. There is a simple toggle switch to select which one of them is the
talker so noone can set both of them talking simultaneously.

NMEA and SeaTalk on same network
 

Manlio wrote in
:

I will have some trouble to
unbury my old sextant !! :-))


I keep my nice sextant with me. The dock usually doesn't move more than
a mile or so when I check it....(c;)

NMEA and SeaTalk on same network
 

Larry wrote in
:

Manlio wrote in
news:kgoks3lt7mrm6s0cavklpprrs2t1sf2kro@ 4ax.com:

I would like to add a second GPS (Raystar 125) connecting its SeaTalk
output signal to the SeaTalk network. This would be meant to be a
reserve in case of failure of the first one. May I leave it in
operation, having GPS data coming from two devices, or it's better to
keep it off and disconnected while the first one is in operation ?

You must NEVER have TWO GPS units talking to the network at the same
time. They will NEVER put out the same data. The results are that
every plotter on the boat goes crazy with the conflicting data
streams, your position jumping from A to B to A to B all the time.

I don't believe this is what actually happens with RayMarine chart-
plotters. From what I've seen, it uses a single talker for the input and
when that input fails, it switches over to the other source.

In the case of multiple compasses, which I have, it averages the reading
between the sources.

-- Geoff
www.GeoffSchultz.org

NMEA and SeaTalk on same network
 

I don't believe this is what actually happens with RayMarine chart-
plotters. From what I've seen, it uses a single talker for the input and
when that input fails, it switches over to the other source.

I know that's what it does when dealing with GPS from sources on different
busses. I've got one on NMEA2000 and the other on regular SeaTalk. It uses
the one on NMEA2k first (and doesn't give me a choice otherwise) and will
fall back to the one on SeaTalk.

In the case of multiple compasses, which I have, it averages the reading
between the sources.

Is there a seatalk-only heading sensor? I've got a heading sensor but it's
attached to the autopilot, and thus only works what that's turned on. I
tend not to use the autopilot but would like a header indicator.

-Bill Kearney

NMEA and SeaTalk on same network
 

"Bill Kearney" wrote in
:

Is there a seatalk-only heading sensor? I've got a heading sensor but
it's attached to the autopilot, and thus only works what that's turned
on. I tend not to use the autopilot but would like a header
indicator.

-Bill Kearney




Sure. Raymarine calls it a "Smart Heading Sensor" and it also includes an
electronic gyro that feeds rate-of-turn data to the system.

http://www.raytechonline.com/product...ion=2&page=389
&product_id=699

Pay particular attention to the instructions on placement and orientation
of the big box with the gyro in it when you install it. The fluxgate is
installed elsewhere so they do not interact. Don't install them next to
each other.

"Lionheart" has this overpriced beast on it and it does work, I suppose.
But, the compass sensor for the B&G "Network" Pilot autopilot works so much
better we hardly ever use it. The B&G Pilot "learns" and corrects its
oversteering shortly after you install it, making its own chart of how to
make smooth turns and compensate for the boat's motion, so the SHS is just
overkill. The B&G self compensates its compass sensor, storing its offsets
very nicely. Compass data to the network comes out of the Pilot computer,
already nicely compensated. The SHS is the backup unit, after comparing
them for a while.

Just like anything else for the boat, bring your high-limit credit card...
(c;