Seatalk-1 bus power

laika

laika

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I'm thinking of upgrading my Raymarine autopilot to a fancy new one. The old one powers the seatalk-1 bus. I'm not upgrading my ST50s. I note the head of the new one accepts seatalk-1 input and provides power to the seatalk-ng bus but no mention of power to the seatlak-1 bus. A dealer told me to buy a separate seatalk-ng to seatalk-1 converter but the specs for that don't mention bus power. I tried asking Raymarine support but no answer after 3 days. Others must have done this. I'm presuming that direct connection to the batteries wouldn't be a good plan. Thoughts?
 
I suspect it probably does power the Seatalk 1 bus and just doesn't mention it in the docs. However, if it turns out not to, there's nothing wrong with supplying the red wire directly via a 2-amp fuse. Seatalk 1 is nice like that :)

Pete
 
So you're both saying that a direct-from-the-battery (well, fused obvs..) unregulated 12v (==12-14.4v) supply is OK? I admit I haven't tried it but somewhere I had in my mind that people used the power out from the AP because it was smoothed and regulated. If that's just nonsense and battery voltage is fine I've not got a problem :-)
 
STng to ST converter powers my ST50 log display no problem. You do not want 2 separate power supplies according to the instructions. If you want to keep the 2 systems completely separate, then you can power both direct from the batteries.
 
laika said:
So you're both saying that a direct-from-the-battery (well, fused obvs..) unregulated 12v (==12-14.4v) supply is OK?
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Correct. Read the manuals, it's what they advise in most cases. Even when you have an autopilot, it's optional whether or not you want to power the bus from it.

My bus is powered from the autopilot because there is no situation where I would want the instruments on but not the pilot (at least on standby), so a single switch in the supply to the pilot brain provides that.

For very large Seatalk buses (larger than most normal boats) they advise connecting both ends to the battery (well, the fuse/switch panel) to avoid volt drop.

Really Seatalk 1 is beautifully simple. +12v (nominal) on red, 0v on black, and yellow idles at +12v but is pulled down to 0v when an instrument has something to say. The instruments have their own protection against any likely misconnection, noise, short-circuit, etc; the worst that's likely to happen is that they temporarily won't work or won't talk to each other, but fix the problem and all will be well again. The data rate is slow enough and has a big enough voltage swing to get through almost anything, and almost all of the messages are stateless so if a few do go missing it doesn't really matter. It's an ideal design for a semi-neglected system on a small scrappy yacht in the real world, provided only that you don't need to transfer vast quantities of data which most of us don't.

Pete
 
prv said:
For very large Seatalk buses (larger than most normal boats) they advise connecting both ends to the battery (well, the fuse/switch panel) to avoid volt drop.

Pete
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Be careful about doing this as it blew up the Seatalk bus on my S3 Autopilot so I can not longer use the ST60 Wind to run the A/P.

Well worth doing some googling about the problem before you try it
 
john_q said:
Be careful about doing this as it blew up the Seatalk bus on my S3 Autopilot so I can not longer use the ST60 Wind to run the A/P.

Well worth doing some googling about the problem before you try it
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Well, I have no need for it as I only have a few instruments. But it's advised in numerous Raymarine manuals, so I'd be surprised if there's really a problem. Can you elaborate on how you managed to damage your autopilot?

Pete
 
prv said:
Well, I have no need for it as I only have a few instruments. But it's advised in numerous Raymarine manuals, so I'd be surprised if there's really a problem. Can you elaborate on how you managed to damage your autopilot?

Pete
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Maybe it is just my set up but bearing in mind my location, my options are limited

I had a “so called Ray Marine Technician",(read fitter not Technician) on board about a separate problem with the A/P to do with the compass.

He looked at the A/P and 3 other ST60+ instruments all supplied with power from the A/P which had been working fine for years and said you must connect both ends to the 12 v so I did using existing cables I have used before

Result was that within 30 seconds of powering up, the other instruments no longer displayed SeaTalk data from the A/P (e.g., no SOG on the speed) and the A/P was not happy with error messages all over the place and not staying on AUTO

I disconnected the A/P Seatalk cable from the ST60+ instruments and now run and power them separately and most things work although I do have to have the speed plugged into the A/P otherwise I get a SPD error message on the A/P.

When I get time I will try and recalibrate the A/P and see if it removes the SPD error
 
Seatalk 1 is the only truly plug and play setup in all the electronics I've ever used, it's the reason I've stuck with Raymarine and can't ever see myself changing from Seatalk 1; the autopilot is an SPX30, the last generation before they went to a self setup and self calibration system which would be nice, but SPX30 works well enough and all the instruments just chat away merrily to one another. What I'd love to do though is get a true Raymarine expert on board to calibrate it, I'm sure I haven't got the autopilot properly set up. Tom Cunliffe said the same about his, got an expert onboard and they sorted it.
 
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