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