Marine Radio Data Question

[NQ6U]

Here's one for you network geeks:

My Standard Horizon (Yaesu) marine VHF radio communicates with my stand-alone GNSS unit via an NMEA 0183 network. Or, at least it used to until I swapped over to a more modern radio a few months back. Now it mostly doesn’t. There is power to the unit and the data bus is easily accessible for testing but I:

1) Don’t know what test equipment I’d need and

2) Probably wouldn’t know what I was looking for anyway.

NMEA 0183 is a simple serial bus that uses the EIA-422 electrical standard and all the data is sent in ASCII characters. Here's the Wikipedia article on the networking protocol: https://en.wikipedia.org/wiki/NMEA_0183

Any suggestions would be appreciated.

[N8YX]

A protocol analyzer is what you seek (sorry for not seeing this earlier).

Let me do some digging around the various sites and I'll point you to the stuff I used to use when debugging 232/422/485 comms.

[N1LAF]

Carlo, You may be able to use a RS-422/RS-232 converter, Connecting the converter R+, R- input lines to the RS-422 R+,R- for one side of the communications, and then connect the converter R+/R- input line to the RS-422 T+/T- lines. Since the communications are in ascii, a terminal program used for RS-232 serial should work just fine. You will not need to connect the converter T+/T- to anything, the converter is used as a receiver only.

Found this, that has convenient screw terminals on the RS-422 side, in stock for $14.95


https://www.serialcomm.com/datasheets/CON-422-PE9.pdf - Datasheet
PDF (https://www.serialcomm.com/datasheets/CON-422-PE9.pdf)

https://www.serialcomm.com/serial_rs232_converters/rs232_to_rs422_converters/rs232_to_rs422_converter/rs232_to_rs422.product_general_info.aspx
Link
(https://www.serialcomm.com/serial_rs232_converters/rs232_to_rs422_converters/rs232_to_rs422_converter/rs232_to_rs422.product_general_info.aspx)

[N8YX]

Here's the series I used to use way back when:

http://hpmuseum.net/display_item.php?hw=1123

And this: https://archive.org/details/FEwinxl

I found a few other models online - new and used. Years ago you used to be able to lease these per week, month, whatever from test equipment suppliers. As cheap as the 495x series are on the used market I'd go that route - unless you find a ParaScope cheap.