127.0.0.1 is the localhost IP address i.e. that is for connecting to services on the local laptop only. I couldn't find a user manual on the PolarNavy site for PolarCOM but the list of features include
Forwarding and receiving data over TCP/UDP network connections
So it should be straight forward to work out how to setup PolarCOM and OpenCPN to send NMEA data from PolarCOM on laptop 1 to OpenCPN on laptop 2.
Open a command prompt on laptop 2 and type ipconfig
, that will list the network devices and the IPV4 addresses for each device. On laptop 1 setup PolarCom to transmit the NMEA data to the IP address for laptop 2.
If you need to know what ports
OpenCPN on laptop 2 is listening and there is no configuration screen
in OpenCPN to set it up then in the command prompt window type netstat /a /n
and that will list the open TCP ports
and their state. Look for a line that has LISTENING in the right hand column.
In the 2nd column is the IP address and port the software is listening on in the format <IP address>:<port number> . In most cases the IP address will be 0.0.0.0 which means listen on all IP addresses on all devices - so use the IP address from ipconfig.
UDP does use ports - it differs from TCP in that it is not stream based (i.e. there is no connection established)