Open Plotter NMEA 0183 parallel connections

[Loonboat]

Hello,
I have a question regarding NMEA 0183 parallel connections, as I recently set up OpenPlotter on a RPi  4B as my secondary chart plotter with the GPS/AIS input coming from my VHF radio and I was wondering if I can still connect my primary chart plotter to the same  NMEA connection on my VHF radio?

The GPS/AIS NMEA 0183 input to my RPI is coming from my Standard Horizon GX2200 VHF radio via a FTDI RS232 serial to USB converter. 

My primary chart plotter is a Garmin echomap 55dv and it gets it’s AIS input from the same VHF radio, however  I’m not sure if I can connect both this chart plotter and my RPi to the same NMEA output from the VHF radio at the same time.  

I’m not very familiar with NMEA connection protocols, so I’ve not tried doing this yet as I’m concerned that it could result in NMEA input/output conflicts, or damage to the NMEA circuitry in the chart plotters and/or VHF radio.

In researching this I  could not find any examples of this specific situation, although I came across questions on NMEA connections in general, and except for particular cases, they seemed to suggest that parallel connections were  not recommended.  

Can anyone help confirm whether or not NMEA connections can be made in parallel for the above situation?  Many Thanks

[SCarns]

NMEA0183 is very "old school." The answer is yes. You can connect a number of "listeners" to one "talker." In your case, you can connect all your NMEA0183 INPUTS of you chart plotter and your RPi to the OUTPUT of the radio. But with 0183, you must take care. The radio input can only listen to one "talker," so you should only hook up the radio input to one device. It's always One Talker/Many Listeners, but not Many Talkers/One Listener. Kind of like my household now that I think of it...

[Loonboat]

Thanks! That’s very helpful, I’ll try setting it up in the next couple of days.