NMEA0183 via USB RS232 to SignalK

[MattMadison]

Hello you great boater community 

please could someone tell me which kind of USB device i do need to connect 16 years old NMEA0183 Airmar transducers (unfortunately no model type is visible) to my raspberry pi 4b to get the data in SignalK?
at the moment they are connected to a very old Furuno Chartplotter and MFD.

after reading a lot i still do not understand which USB hardware i really need to get that old transducers to work with SignalK, i want to get the depth data from one, and the depth/speed/temperature data of the other transducer.
therefore i would connect 2 of the PL2303HX USB to TTL modules via a USB Hub to the raspberry and connect the transducer wires to the corresponding pins on the USB Device.
for example: PL2303HX USB to TTL UART RS232 COM Kabel-Modul Converter (https://www.amazon.de/gp/product/B00WMJN...28QH&psc=1)? 
would it work with that USB devices?

thanks a lot and happy boating to all 

Matt

[Luckbert]

Hello,
I use this adapter successfully.

 klick 



You can get it not only from AliExpress but also from other selling platforms on the Internet.

Greetings Juergen

[MattMadison]

thank you very much for the quick reply and information Juergen!

do you know if it is possible to get the NMEA0183 also via RS232?
or is it only possible via RS422?

i just found that the PL2303HXD:
Supports RS-232 serial interface with Programmable baud rate from 75 bps to 12 Mbps
Supports RS422/RS485 interface
i only find specs for PL2303 and PL2303HXD but no information about the PL2303HX, so i am not sure if RS422 is really supported.

greetings, Matt

[Luckbert]

Sorry, I can't help you there.

I only use the one pictured.

Greetings

[baltika_no_9]

thank you very much for the quick reply and information Juergen!

do you know if it is possible to get the NMEA0183 also via RS232?
or is it only possible via RS422?

i just found that the PL2303HXD:
Supports RS-232 serial interface with Programmable baud rate from 75 bps to 12 Mbps
Supports RS422/RS485 interface
i only find specs for PL2303 and PL2303HXD but no information about the PL2303HX, so i am not sure if RS422 is really supported.

greetings, Matt

If you're sure it's RS232 you need then yes it is possible to transfer nmea0183 via RS232. I do exactly that and plug the USB into my Pi running OpenPlotter and configure the serial connection. There are several cables or adapters that can do this. I prefer to use the FTDI chip rather than PL2303 but that is a personal matter only, the drivers are more universally available in my experience.  Forget TTL.

The cable I use is the USB-RS232-WE-1800-BT_0.0 or equivalent (note the 0.0 which means 0V, you get them for 3.3V or 5V that that is not required). You connect the nmea out of your device to the Rx wire of the adapter, nmea in to Tx and GND to GND, Baud rate is likely to be 4800 unless you've got AIS traffic.

Where are you? I have a spare one you could try if you like.

[baltika_no_9]

Given the devices you're hoping to connect you won't need the Tx wire on the USB RS232 cable. You should have an nmea out + which goes to the Rx wire of the cable (usually yellow if it's the one I suggest but check). The nmea out - should go to the GND of the RS232 cable, the black wire.

[MattMadison]

thank you very much guys! i found out that my equipment is a kind of special setup with Furuno Network Sounder / FishFinder and so on. anyway i want to sell the whole Furuno Equipment, i simple add the 2 transducers to the set and will put in 2 new NMEA2000 transducers and directly connect them to the NMEA2000 bus.
thanks!