Can anyone help
I have a Raymarine ST60 Multi and want to get NMEA data (Wind & Depth) into
the 9 pin serial port on my laptop. If the laptop is not connected to
anything at all (including power supplies) this works fine. If I connect it
to the boats 12v supply via a cigarette type laptop power supply, or an
inverter using the normal laptop power lead I get nothing.
Equally if I connect the USB port via a Serial to USB lead to the GPS and
AIS input I immediately loose the NMEA input.
I have been told I need to use an optocoupler (optical isolator) and have
bought a 4N25 chip.
Can anyone suggest what the problem is and / or give me a circuit diagram of
how to use this optocoupler

many thanks

Phil

Phil,
What you need is a Seatalk to NMEA converter. The Raymarine ST60 output
is seatalk NOT NMEA. If you use the Raymarine navigation software
package then it will decode the seatalk data stream from the ST60
directly without the converter.
krj.

Phil Stanton wrote:
Can anyone help
I have a Raymarine ST60 Multi and want to get NMEA data (Wind & Depth) into
the 9 pin serial port on my laptop. If the laptop is not connected to
anything at all (including power supplies) this works fine. If I connect it
to the boats 12v supply via a cigarette type laptop power supply, or an
inverter using the normal laptop power lead I get nothing.
Equally if I connect the USB port via a Serial to USB lead to the GPS and
AIS input I immediately loose the NMEA input.
I have been told I need to use an optocoupler (optical isolator) and have
bought a 4N25 chip.
Can anyone suggest what the problem is and / or give me a circuit diagram of
how to use this optocoupler

many thanks

Phil

The ST60 Multi has SeaTalk in and NMEA In and Out. As I said, I can read it
fine providing nothing else is connected to the Laptop

Phil
"krj" wrote in message
...
Phil,
What you need is a Seatalk to NMEA converter. The Raymarine ST60 output is
seatalk NOT NMEA. If you use the Raymarine navigation software package
then it will decode the seatalk data stream from the ST60 directly without
the converter.
krj.

Phil Stanton wrote:
Can anyone help
I have a Raymarine ST60 Multi and want to get NMEA data (Wind & Depth)
into the 9 pin serial port on my laptop. If the laptop is not connected
to anything at all (including power supplies) this works fine. If I
connect it to the boats 12v supply via a cigarette type laptop power
supply, or an inverter using the normal laptop power lead I get nothing.
Equally if I connect the USB port via a Serial to USB lead to the GPS and
AIS input I immediately loose the NMEA input.
I have been told I need to use an optocoupler (optical isolator) and have
bought a 4N25 chip.
Can anyone suggest what the problem is and / or give me a circuit diagram
of how to use this optocoupler

many thanks

Phil

On Tue, 17 May 2005 18:30:19 -0400, krj
wrote:

Phil,
What you need is a Seatalk to NMEA converter. The Raymarine ST60 output
is seatalk NOT NMEA. If you use the Raymarine navigation software
package then it will decode the seatalk data stream from the ST60
directly without the converter.
krj.

Phil Stanton wrote:
Can anyone help
I have a Raymarine ST60 Multi and want to get NMEA data (Wind & Depth) into
the 9 pin serial port on my laptop. If the laptop is not connected to
anything at all (including power supplies) this works fine. If I connect it
to the boats 12v supply via a cigarette type laptop power supply, or an
inverter using the normal laptop power lead I get nothing.
Equally if I connect the USB port via a Serial to USB lead to the GPS and
AIS input I immediately loose the NMEA input.
I have been told I need to use an optocoupler (optical isolator) and have
bought a 4N25 chip.
Can anyone suggest what the problem is and / or give me a circuit diagram of
how to use this optocoupler

many thanks

Phil


Presumably he already has that covered, since he says it works fine
until he hooks up power. PC serial port signals are ground
referenced. NMEA (RS422) is differential. I am way over my head
here, but I'd guess hooking boat 12v power to the laptop is connecting
one of the RS422 signal lines to boat ground, which could easily cause
your problem. It's not necessarily just an isolation problem, though.
RS422 and RS232 are not guaranteed to work together, isolated or
otherwise. Take a look he

http://www.bb-elec.com/bb-elec/liter...83v2c_4502.pdf

for a packaged solution. It sounds as if a quality multiplexor would
solve your problem as well.

__________________________________________________ __________
Glen "Wiley" Wilson usenet1 SPAMNIX at world wide wiley dot com
To reply, lose the capitals and do the obvious.

Take a look at cpRepeater, my NMEA data integrator, repeater, and
logger at http://www.worldwidewiley.com/

Phil Stanton wrote:
Can anyone help
I have a Raymarine ST60 Multi and want to get NMEA data (Wind &
Depth) into the 9 pin serial port on my laptop. If the laptop is not
connected to anything at all (including power supplies) this works
fine. If I connect it to the boats 12v supply via a cigarette type
laptop power supply, or an inverter using the normal laptop power
lead I get nothing.
Equally if I connect the USB port via a Serial to USB lead to the GPS
and AIS input I immediately loose the NMEA input.
I have been told I need to use an optocoupler (optical isolator) and
have bought a 4N25 chip.
Can anyone suggest what the problem is and / or give me a circuit
diagram of how to use this optocoupler

many thanks

Phil

You don't say whether you have grounded the nmea output to pin 5, but I have
found that if you don't do this you get no signal, even when pins 2 &3 are
receiving/transmitting. On really old laptpos/PC's we used to also short out
pins 4 & 6, plus 7 & 8, to prevent the laptop thinking it was connected to a
modem with buffering protocol, no longer necessary.

Dennis.

Thanks for that, Dennis.
I have not tried to output to the ST60 Multi - one thing at a time. The +
input from the Multi is connected to pin 2 and the - input from the Multi is
connected to pin 5.
I will try shorting out the pins you suggest

Phil


"Dennis Pogson" wrote in message
...
Phil Stanton wrote:
Can anyone help
I have a Raymarine ST60 Multi and want to get NMEA data (Wind &
Depth) into the 9 pin serial port on my laptop. If the laptop is not
connected to anything at all (including power supplies) this works
fine. If I connect it to the boats 12v supply via a cigarette type
laptop power supply, or an inverter using the normal laptop power
lead I get nothing.
Equally if I connect the USB port via a Serial to USB lead to the GPS
and AIS input I immediately loose the NMEA input.
I have been told I need to use an optocoupler (optical isolator) and
have bought a 4N25 chip.
Can anyone suggest what the problem is and / or give me a circuit
diagram of how to use this optocoupler

many thanks

Phil

You don't say whether you have grounded the nmea output to pin 5, but I
have
found that if you don't do this you get no signal, even when pins 2 &3 are
receiving/transmitting. On really old laptpos/PC's we used to also short
out
pins 4 & 6, plus 7 & 8, to prevent the laptop thinking it was connected to
a
modem with buffering protocol, no longer necessary.

Dennis.

Phil Stanton wrote:
Can anyone help
I have a Raymarine ST60 Multi and want to get NMEA data (Wind & Depth) into
the 9 pin serial port on my laptop. If the laptop is not connected to
anything at all (including power supplies) this works fine. If I connect it
to the boats 12v supply via a cigarette type laptop power supply, or an
inverter using the normal laptop power lead I get nothing.
Equally if I connect the USB port via a Serial to USB lead to the GPS and
AIS input I immediately loose the NMEA input.
I have been told I need to use an optocoupler (optical isolator) and have
bought a 4N25 chip.
Can anyone suggest what the problem is and / or give me a circuit diagram of
how to use this optocoupler

many thanks

Phil



Classic combination of mixing (incompatible) RS-232 and RS-422 signals.

If you were trying to do this the other way around (RS-232 to RS-422)
you could try connecting the RS-232 "Ground" to the ST60's "-" input, as
the ST60 has isolated inputs and no ground loop would be created.

In the case of ST60 output to RS232 input i'm not so sure you can do
this; you may end up with damaged hardware if you tried connecting the
RS-232 "ground" level to the ST60's "-" output did you. However, as you
are experiencing, connecting just the "A" output doesn't work.

You could risk trying to tie the ST60's "-" output to the RS-232 ground...

The other alternative, if you are not an electrical engineer and unable
to wire up the optocoupler, I suggest you get a RS-422 to RS-232
converter, for instance as present in the various NMEA multiplexers.

-- Kees

Phil Stanton wrote:
Thanks for that, Dennis.
I have not tried to output to the ST60 Multi - one thing at a time. The +
input from the Multi is connected to pin 2 and the - input from the Multi is
connected to pin 5.
I will try shorting out the pins you suggest

Phil

Aha, this information (- connected to pin 5) combined with the fact that
if the laptop's internal zero is no longer floating compared to the boat
zero (= connect charger) means you are introducing a ground loop.

Face the facts, you need an optocoupler. If you don't know how to build
an appropriate circuit, get a RS-422 input port or an NMEA Multiplexer.

-- Kees

Thanks Kees

Looks as if I will have to pay through the nose to get an optocoupler, but
have bitten the bullet and ordered one.
Thanks for everyone's input

Phil
"Kees Verruijt" wrote in message
...
Phil Stanton wrote:
Can anyone help
I have a Raymarine ST60 Multi and want to get NMEA data (Wind & Depth)
into the 9 pin serial port on my laptop. If the laptop is not connected
to anything at all (including power supplies) this works fine. If I
connect it to the boats 12v supply via a cigarette type laptop power
supply, or an inverter using the normal laptop power lead I get nothing.
Equally if I connect the USB port via a Serial to USB lead to the GPS and
AIS input I immediately loose the NMEA input.
I have been told I need to use an optocoupler (optical isolator) and have
bought a 4N25 chip.
Can anyone suggest what the problem is and / or give me a circuit diagram
of how to use this optocoupler

many thanks

Phil

Classic combination of mixing (incompatible) RS-232 and RS-422 signals.

If you were trying to do this the other way around (RS-232 to RS-422) you
could try connecting the RS-232 "Ground" to the ST60's "-" input, as the
ST60 has isolated inputs and no ground loop would be created.

In the case of ST60 output to RS232 input i'm not so sure you can do this;
you may end up with damaged hardware if you tried connecting the RS-232
"ground" level to the ST60's "-" output did you. However, as you are
experiencing, connecting just the "A" output doesn't work.

You could risk trying to tie the ST60's "-" output to the RS-232 ground...

The other alternative, if you are not an electrical engineer and unable to
wire up the optocoupler, I suggest you get a RS-422 to RS-232 converter,
for instance as present in the various NMEA multiplexers.

-- Kees