Hi group,

I have a question concerning the update rate of a SeaTalk bus.

I have a GPS ( NMEA ), a ST60 tridata ( SeaTalk ) and a SeaTalk Autopilot.

In order to exchange Data between NMEA - Seatalk I built a
single chip computer ( Atmega32 ).

Ok - now i can translate NMEA Sentences to SeaTalk datagrams and
vice versa.
The GPS sends its information about ever two seconds.
But how often should i sent data to the SeaTalk bus.

My boat is somewhere far away in in winter storage. So currently
i can't just go to the boat and check myself.

Currently my software just sends updates to seatalk, whenever
NMEA data changes ( And vice versa ).
But when the boat stands still, the speed or position
never changes. This can't be correct - i guess.

So - if somone out there knows how often instuments on SeaTalk transmit
data - please let me know.

Thank's
Frank

btw. Hardware and Software are NOT RAEDY. I'm still working on it.
But - if someone is interested and would like to continue progamming
on it or just playing with it - It's free.
On http://www.tklinux.de you can find more about software and hardware.

Use NMEA Talker for testing available on www.sailsoft.nl I do as well!
What is the difference between your product and available from Raymarine
apart I hope from the cost.

Regards,
Gerard van Toornenberg, N 52° 51.355' E 005° 41.835' , Lemmer, Nederland
E-mail

Homepage www.gpspossmart.nl

"Frank" schreef in bericht
...
Hi group,

I have a question concerning the update rate of a SeaTalk bus.

I have a GPS ( NMEA ), a ST60 tridata ( SeaTalk ) and a SeaTalk Autopilot.

In order to exchange Data between NMEA - Seatalk I built a
single chip computer ( Atmega32 ).

Ok - now i can translate NMEA Sentences to SeaTalk datagrams and
vice versa.
The GPS sends its information about ever two seconds.
But how often should i sent data to the SeaTalk bus.

My boat is somewhere far away in in winter storage. So currently
i can't just go to the boat and check myself.

Currently my software just sends updates to seatalk, whenever
NMEA data changes ( And vice versa ).
But when the boat stands still, the speed or position
never changes. This can't be correct - i guess.

So - if somone out there knows how often instuments on SeaTalk transmit
data - please let me know.

Thank's
Frank

btw. Hardware and Software are NOT RAEDY. I'm still working on it.
But - if someone is interested and would like to continue progamming
on it or just playing with it - It's free.
On http://www.tklinux.de you can find more about software and hardware.

Thank you for your reply

G. van Toornenberg wrote:
Use NMEA Talker for testing available on www.sailsoft.nl I do as well!

This will help me with the NMEA Part.
But my current major problem is on the SeaTalk side.
How often should i send my SeaTalk datagrams.


What is the difference between your product and available from Raymarine
apart I hope from the cost.

Well - if it's only the cost - it would be enough for me :-)

No - it's hobby, understanding things, beeing able to make it myself.

AND - I have the source codes. I can change and expand it to whatever I
want.
I personally don't need any sentencetype Raymarine's NMEA Bridge has.
But I would like to have other functions. And I wouldn't get them from the
Raymarine device. Like - switch on diffrent lights, when i press the Light
button on my ST60. Or ring a louder alarm bell, wenn low water alarm goes
off. .... or things like that.

Regards
Frank

Sorry - i made a mistake

I wrote :
I personally don't need any sentencetype Raymarine's NMEA Bridge has.

but i mean
I personally don't need ALL THE sentencetypes that Raymarine's NMEA Bridge
can handle.


Frank

On Mon, 02 Feb 2004 00:58:58 +0100, Frank
wrote:

Sorry - i made a mistake

I wrote :
I personally don't need any sentencetype Raymarine's NMEA Bridge has.

but i mean
I personally don't need ALL THE sentencetypes that Raymarine's NMEA Bridge
can handle.


Frank

Seatalk is too slow, even for Raymarine! I believe it updates
1/second. Case in point.....go to:
http://www.raymarine.com/raymarine/S...81198_1www.pdf
and download the owner's manual for our Raymarine Smart Heading Sensor
(compass with little gyro unit).
Scan down the PDF manual to page 16, section 2.4.
where it says:
2.4 Connecting to Pathfinder Plus
You need to connect the GyroPlus 2 unit to the Pathfinder Plus using both
NMEA and SeaTalk:
• the SeaTalk connection allows the Pathfinder Plus unit to calibrate
the compass
• the NMEA connection provides the fast heading information for
MARPA and radar/chart overlay

The NMEA update rate is 10 Hz....10 times faster than Seatalk.

I'm still trying to get the Smart Heading Sensor compass to calibrate
itself. Currently, Lionheart is using the fast-calibrating B&G
compass sensor of the B&G Network Pilot autopilot for network compass
heading information. It calibrates much easier than the SHS, so far.
I'm going to try a different mounting position for the Raymarine
compass sensor, which after 10 turns still starts to calibrate, then
whips around out of control on every turn.....Nothing magnetic or
wiring anywhere near it....(sigh)

Crew gets itchy if the chief engineer insists on "one more slow turn"
on a nice day....(c;......delaying this project with offers of booze
and food and sex. The SHS can wait another day....(c;



Larry W4CSC

No, no, Scotty! I said, "Beam me a wrench.", not a WENCH!
Kirk Out.....

On Mon, 02 Feb 2004 01:35:38 GMT, (Larry W4CSC) wrote:


I'm still trying to get the Smart Heading Sensor compass to calibrate
itself. Currently, Lionheart is using the fast-calibrating B&G
compass sensor of the B&G Network Pilot autopilot for network compass
heading information. It calibrates much easier than the SHS, so far.
I'm going to try a different mounting position for the Raymarine
compass sensor, which after 10 turns still starts to calibrate, then
whips around out of control on every turn.....Nothing magnetic or
wiring anywhere near it....(sigh)

Open the RayMarine sensor and see what's going on inside.

I had an AutoHelm ST50 compass on a previous boat, and had a screwy
problem like that - the internal gimbals had got tangled somehow, so
the sensor was being held at some strange angle. It was easily fixed,
once I could see inside.






--
Peter Bennett, VE7CEI
peterbb (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

"Frank" wrote in message
...
Hi group,

I have a question concerning the update rate of a SeaTalk bus.

I have a GPS ( NMEA ), a ST60 tridata ( SeaTalk ) and a SeaTalk Autopilot.

In order to exchange Data between NMEA - Seatalk I built a
single chip computer ( Atmega32 ).

Ok - now i can translate NMEA Sentences to SeaTalk datagrams and
vice versa.
The GPS sends its information about ever two seconds.
But how often should i sent data to the SeaTalk bus.

If you are able to read from the Seatalk bus, you can see how often other
instruments send their data, right?

My boat is somewhere far away in in winter storage. So currently
i can't just go to the boat and check myself.

Currently my software just sends updates to seatalk, whenever
NMEA data changes ( And vice versa ).

I would send Seatalk data for every received NMEA sentence. Otherwise you
would never know when the NMEA source has stopped sending (faulty hardware).

But when the boat stands still, the speed or position
never changes. This can't be correct - i guess.

I find that hard to believe. I have a GPS sitting on my desk and the speed
and bearing constantly vary, caused by the random 'noise' on a GPS fix.

Again, translate every sentence when it comes in and transmit it. Since
Seatalk is binary, the datagrams are much shorter that NMEA sentences, so
your bandwidth is higher.

Meindert

Meindert Sprang wrote:


If you are able to read from the Seatalk bus, you can see how often other
instruments send their data, right?

Right - but as I a wrote, i don't have a SeaTalk instument here.

May Boat is sitting dry in winter storage. And I would like to continue my
work.
And all I have on Board is Speed/Depth/Water Temperature and an Autopilot -
all Instruments that don't work without Water.

I would send Seatalk data for every received NMEA sentence. Otherwise you
would never know when the NMEA source has stopped sending (faulty
hardware).

I guess i'll do that.


But when the boat stands still, the speed or position
never changes. This can't be correct - i guess.

I find that hard to believe. I have a GPS sitting on my desk and the speed
and bearing constantly vary, caused by the random 'noise' on a GPS fix.

Again, translate every sentence when it comes in and transmit it.

Ok. I will try with sending every time NMEA data come in.


Since Seatalk is binary, the datagrams are much shorter that NMEA
sentences, so your bandwidth is higher.

Good thought !!



Thank's for your help

Frank