[TG] [TG11] Integrating legacy Seatalk devices

[Wdeertz]

See the attached schematics which I've tried to capture everything in my new system after adding 2 Axiom Pro mfd's, AR200 unit, several IP cameras and a Quantum 2 radar. I added two Seatalk to SeatalkNG converters to my network with one being dedicated to the 400G autopilot and the other for my ST60 depth gauge. Everything in the pilothouse is working fine but none of the 3 seatalk devices on the flybridge (namely rudder angle indicator, wireless autopilot remote and autopilot receiver) is working.

There is a rudder indicator wired directly to the 400G autopilot and this works fine. The signal is being sent throughout the network as both mfd's properly show the rudder movement.

I've tried connecting the sea talk cable from the flybridge to the ST60 depth gauge (#1 on schematic highlighted in green) but this doesn't power the devices on the flybridge and stops the depth gauge from working.

I also tried connecting the flybridge sea talk cable to the autopilot network branch (#2 on schematic highlighted in green) but this stopped the ST6001 control unit from working.

How should I connect the flybridge seatalk devices to the network? Do I need another Seatalk to SeatalkNG converter to feed the flybridge devices into?

[Tom - Raymarine - Moderator]

Hello Wdeertz,

To start, I'll make a couple of comments about this drawing:

1. You should have a single Seatalk1 network, with a single convertor. Multiple Seatalk networks and convertors is highly likely to cause problems. Definitely don't add a third.
2. I'd advise caution using non-marine network devices on a boat, particularly in a navigation network. They're generally not tolerant of the shock & vibration, humidity, temperature cycling, saline mist or power-supply instability of a marine environment, and generally don't comply with marine EMC standards. I heard of a boat here in Australia that suffered a fire at sea because of a non-marine network switch that didn't cope with the marine environment (and wasn't adequately circuit-protected.)
   

The correct way to do this is to remove one of your convertors and join the Seatalk1 networks, however it appears that you have another problem: if joining the cable marked no.1 powers down the ST60 Depth and fails to power the flybridge devices, then it sounds as if you have either a high-resistance connection in the cabling (causing a significant voltage drop) or something drawing significant current in the flybridge Seatalk1 system. The flybridge devices should power up and work whether they're connected via the ST6001 or the ST60 Depth. You need to find and fix this issue first before the rest of the system will work correctly.

Regards,
Tom

[Wdeertz]

Tom, ok I made it over to the boat and was able to get all devices to work when I connected everything inside the pilothouse using shorter cables. See attached schematic. It seems that there is too much resistance on the 15 foot cable going to the flybridge as you suggested. Can I add supplemental 12v power for the flybridge devices? If so which pins on the ST cable should be 12 +/-?

Also, looking at my schematic do I have 5 or 6 devices? Not sure if the autopilot wireless remote counts as it links to the wireless transmitter.

-------------- earlier post:

Tom, ok I went back and reread the St to StNG converter manual and do not see where it indicates autopilot and non-autopilot St devices need to be separated. I think I may have read it somewhere on the forum which is why I asked the question in the product selection forum.

So if I understand correctly I can have up to 5 SeaTalk devices on this spur. The power will be provided by the 400G computer. See the attached diagram, does this look like it will work?

What i’m A little confused by is the manual says power shouldn’t be provided from both the SeaTalk spur and the SeaTalkNG network. Will the 400G provide power to the SeaTalkNG devices on the network?

-------------- earlier post:

Tom, thanks for the reply. I’m confused as when I was scoping out this project I asked in the product selection forum about integrating legacy SeaTalk devices into a SeaTalkNG network. Chuck (see http://forum.raymarine.com/showthread.php?tid=8143) confirmed in this posting that all SeaTalk autopilot devices should be to a separate St to StNG converter and St non-autopilots devices to a separate converter.

Are you now saying that all St devices should go through one converter?

[Tom - Raymarine - Moderator]

Hello Wdeertz,

Now we start to get into the realm of personal preference and experience.

Quote:Chuck (see http://forum.raymarine.com/showthread.php?tid=8143) confirmed in this posting that all SeaTalk autopilot devices should be to a separate St to StNG converter and St non-autopilots devices to a separate converter.

Are you now saying that all St devices should go through one converter?

My view is that you should have the fewest networks possible in the system, with the fewest connection points, and no duplication of network types. My reasons are:

• Not all data is bridged through the convertor in all circumstances, due to limitations in the ~30YO design of ST1. Examples include depth unit selection and magnetic variation. If you separate networks then more of the system will potentially use the wrong value.
• latency: every translation between networks involves reception, decoding, re-encoding and a wait for a transmission slot onto the other network: these delays can add up when you have multiple links to a slow network such as ST1 so that, for example, the wind or BTW data your pilot's steering to is out of date by the time it's received.
• ST1 'backing-off': ST1 devices are designed to 'back-off' and not transmit a particular data type (e.g. depth) if they see the same data already on the network. If you have multiple networks then you can find data being echoed back to the transmitting device, which then backs off and stops transmitting.
• It doesn't look like a risk in your network, but multiple connection points are a classic cause of data loops: if you have data going in a circle between different networks (e.g. STNG > ST1 > NMEA0183 > STNG) then you can get either backing-off (no data) or worse looped data (the same static value continuously cycling round - a problem if this is depth or GPS.)
  

Quote:Tom, ok I made it over to the boat and was able to get all devices to work when I connected everything inside the pilothouse using shorter cables. See attached schematic. It seems that there is too much resistance on the 15 foot cable going to the flybridge as you suggested. Can I add supplemental 12v power for the flybridge devices? If so which pins on the ST cable should be 12 +/-?

Unless your supply voltage is really marginal, that's not just normal voltage drop but a fault in that cable. Don't attempt to work around a cable fault by adding another power connection:

1. If the problem is simply high-resistance then you provide multiple paths for power that will be at different potentials (voltages) due to the differing cable runs, the high-resistance connection between them and the different loads on either side of that connection. Depending on the instantaneous load from one moment to the next on either side of the join you will get differing current flow, and therefore voltage. Constantly varying voltage is also called electrical noise. This goes double if one of the power points is not straight off the battery but a switchmode supply as in your course computer.
2. Fuse protection. How do you choose an appropriate fuse rating for each power point: the whole network, just the half on that side of the high-resistance join? Wrong fuse ratings are not cool.
3. What if the problem in the cable isn't simply a high-resistance connection but a developing/partial short that's pulling down the supply voltage (non-infinite resistance between +12 and 0V)? By adding another power supply you mask that problem without solving it, and - presumably - add a second fuse which will need to blow in the event that the, say, brittle break in your cable sheath which is allowing red and shield to start bleeding current across through the foil wrapper opens up a little more and allows a full short.
   

Because of point 1 alone, you should only ever have a single point of power in any combined ST1, STNG network. (the NMEA2000 spec says it's ok to have multiple points for power as long as each one is fully isolated: if you don't know whether your supplies are isolated, they aren't.) When I say point of power, I'm only referring to the power for the network itself, not power for high current devices (MFDs, pilots etc.) connected to that network - they still need their own power.

It's up to you where you choose to power - though it ought to be close to the centre of the system current load to minimise voltage drop to the ends - but make sure it's in one place only. If you pull your ST1 / STNG fuse then instrument/pilot displays, GPS antennas etc. should power down: if they don't then you have multiple power paths.

Regards,
Tom

[Wdeertz]

Tom, thanks for the explanation, this was most helpful. I can see the benefits of only having one Seatalk network to avoid latency and the other problems you noted.

I have all ST devices connected through one network and everything seems to be working properly (I discovered the ST cable going to the flybridge had a short so once I corrected this all devices on the flybridge started working).

The only issue relates to a strange power phenomenon. See attached "as is" schematic. I have the ST6001 connected to the 400G Seatalk B connector with the red wire connected. A voltmeter confirms 12v across the red wire and screen wire. When I power up the autopilot the ST6001 and ST60 gauges do not come on as I expected, however, once I provide power to the STNG network everything works fine. I'm not sure why the Seatalk B connector is not powering the ST6001 and ST60 independently of the STNG network power. Any ideas?

Upon further reading the forum I came across another posting which had me redraw my network so the ST6001 is powered by Seatalk A off of the 400G while Seatalk B is connected without the red wire so that spur is powered by the STNG side. See my "to be" schematic. I haven't made it over to the boat to try this but would this sort of setup be preferable?

Thanks

[Tom - Raymarine - Moderator]

If you measure resistance with your multimeter between the red terminals on the two Seatalk connectors on your T400G, you'll find that they're connected (<<1 ohm), meaning that if you connect 12V on one (via STNG), that should also power up the ST6001 connected to the other. If it doesn't then you have a fault somewhere - excess current being drawn or an open-circuit inside the 400G for example.

When you measured 12V being output from the 400G, was that loaded (ST6001 connected) or unloaded? If the latter, what do you see when the ST6001 (only) is connected?
Seeing a particular voltage does not mean that you can draw sufficient current to power a device - if you had a cracked solder joint or some corrosion somewhere for example then you might see 12V under no load but 1 or 2V when a small load was applied.

To reiterate, you should only ever have a single point of power in a combined ST1, STNG network. If you're considering multiple power supplies then you have another problem that you should solve rather than attempt to work around.

Regards,
Tom

[Wdeertz]

Tom, i’ve Gotten everything connected and it appears to be working with one exception. Whenever I do an auto route on the axiom pro it creates the route then I move the boat to somewhere on the route and hit the “auto” button on the ST6001 control unit. The boat starts with the heading but doesn’t respond once the first waypoint is received. In other words it continues on its existing heading rather than responding to the next waypoint heading per the axiom pro auto route.

Does the axiom pro not send the waypoint info out the STNG network via the converter?

Should I be using the NMEA0183 inputs on the autopilot instead?

Thanks

[Tom - Raymarine - Moderator]

Hi Wdeertz,

The problem here is just that you're pressing Auto, which means simply steer to compass heading. What you need is Track mode instead, which means to steer to waypoint data. The pilot doesn't automatically switch from Auto to Track mode when waypoint data is available because sometimes people want to use a waypoint/route on the chartplotter as a guide but still steer 'manually'.

If you press Track on the ST6001 then you should get a series of beeps and a request to acknowledge that the planned course change (e.g. Stbd 045) is safe. You have a look to make sure that it is, and then press Track a second time after which the pilot takes control.

If you press Track and get an alarm 'No data', you may need to set a manual magnetic Variation in the ST6001, because the convertor does not pass this through. The pilot measures heading in magnetic and the chartplotter plots courses in true so variation is required in order to steer to a magnetic bearing-to-waypoint.

Regards,
Tom

[Wdeertz]

Tom, thanks, your suggestion was spot on.