I cannot get the seatalk to function on the chartplotter 320 GPS ,I have it
connected on the Seatalk daisy chain connected to Autohelm ST 50 upgraded to
ST55 and Autohelm auto pilot. As soon as I plug in the Seatalk cable to the
input on the 320 ,the TRUE wind crashes on the wind instrument .I have
checked every connection everywhere .Could it be a configuration problem in
the setup Menu? Help

"David Lapp" wrote in
:

Seatalk daisy chain

All the wires in a Seatalk are in parallel, not "daisy chained"....

If the wires aren't crossed up, the 320 is faulty. Being in parallel, if
you disconnect any one Seatalk instrument, all the other Seatalk
instruments still talk to each other. The only data missing is data the
unplugged instrument was providing.

If the cable to the 320 were cross wired, however, it would not effect the
network until you connected it to the 320, where, say, the 320 were
grounding the data line, or the data line were hooked to +12V. Either way,
it would be "bad" for the other instruments trying to pull it up or down,
but not totally destructive as they all have series resistance to limit the
loading on a shorted Seatalk.

How many Seatalk instruments are all connected in parallel, anyway? There
IS a limit to how many simultaneous instruments seatalk can drive, but I
don't remember what it is....maybe 16? It's not data I use daily...sorry.

Pull the 320 cable off the Seatalk net. Verify each wire actually connects
to the 320 pin you think it should with an ohmmeter. Then, plug it into
the 320 (still disconnected from the network and hanging free). Boot the
320. Check that there is +12V on the +12V wire, ground on the ground wire
and you should be able to see the meter go crazy from the data from the
data wire to the ground wire. This will verify the connection before
hooking it to the seatalk net....

Larry wrote:
"David Lapp" wrote in
:

Seatalk daisy chain

All the wires in a Seatalk are in parallel, not "daisy chained"....

Actually most seatalk networks have there cables "daisy chained".
Most Raymarine instruments offer two Seatalk connectors for conveniance,
which of course are just connected in parallel internally.

Pull the 320 cable off the Seatalk net. Verify each wire actually connects
to the 320 pin you think it should with an ohmmeter. Then, plug it into
the 320 (still disconnected from the network and hanging free). Boot the
320. Check that there is +12V on the +12V wire, ground on the ground wire

The 320 does _not_ provide +12v on the seatalk bus. The +12v pin on
the seatalk output is not connected. You just need to connect the
seatalk data line (yellow wire in Raymarine cables) and ground to the
network. Or use a ready-to-use cable with a seatalk connector on both
ends.

Regards,

Roel.