Originally Posted by espen
I am also trying to find out this stuff. My depth
sounder cable is only a coaxial cable, would this be possible to connect directly to the Rx pin and ground on the raspberry pi GPIO pins? Or do I need the usb to rs232 (or 422) ? If so , since it is only a coax cable , what pins should be connected to the rs232?
The openplotter works great with the gps usb dongle. Super nice system! !
Probably not, but I'm not an expert. My depth sounder also only had a coaxial cable, but that wasn't an NMEA-0183 stream. It connected to the display, which I think then also had an output cord, but I can't remember. I ended up getting a new one instead which houses everything in the unit itself (as in, it had a Tx+ and a Tx- wire).
Now, if you are interested in connecting your instruments to your computer, the easiest way is to use a USB to RS-422 converter (or USB to Serial
converter, depending on how your depth sounder outputs information). You may want to review this background article on NMEA-0183 and computers
), and then this guide on interfacing NMEA-0183 with a Raspberry Pi (King Tide Sailing: A Raspberry Pi Wireless NMEA-0183 Multiplexer (USB GPS, Digital Compass, and Sailboat Instrument Input)
). If you're not going to use any python scripts to filter the data, you can still follow that guide, only you'll just have OpenCPN look at that particular USB/Serial port, just like it does for a USB GPS dongle.