Unreadable output from USB-RS422 Cable

[alexl04]

Dear reader,

First of all, thanks for your time reading this. in advance much appreciated

I just started exploring Openplotter and its possibilities regarding NMEA0183 over Wifi/TCP. Unfortunately I have some troubles with receiving/reading data from an old GPS for which I sincerely would like to request some help from someone who knows what I'm doing wrong. 

To start my goal is to use the RMC and ZDA data from an old but still proper working Geonav Wide 7. The manual of this device tells me that it is able to spit out this data via the NMEA 0183 protocol.

So I bought an USB-RS422-WE-1800-BT Cable and connected:
- the DATA+ Output cable from the Geonav with the DATA+ Input cable from the RS422,
- and DATA- Output cable from the Geonav with the DATA- Input cable from the RS422.

The green led from the RS422 USB cable indicates that it is doing something. However, unfortunately Openplotter is unable to Identificate Automatically the type of data input. I tried all possible settings but without success.

So digged a little further and (for convenience) installed on my macbook software "Serial" and the drivers of the FTDI chip of the RS422 Cable. It shows me that it receives or translates unreadable data. It looks like this:

xxxx`x~~ff`x~fxffxx`xx~fxff憆ff?x<x`xxf3f~~xxxx~ff~xxxxf<`xffxx~wf~xxxxf3f<`3xxf?f3xxx`x`xffxx~fxxxxxxf3<x~ffϘxxxxf<~f~fxxxxffxϘ~x`xxxwxxxφxx~`xfϘfxxxxf~x<fx~f~fx^xxf~fx~xx~~3~fxxxxf~ff?<Ɔxx?fff>xxxff`xxxxf~fxx~x`߆v~xx3x<`~~ffxxxfffx~xff

What do I wrong?

Hopefully its something silly or did I bought the wrong RS422? There is definitely a lot to learn.

Thanks for your help in advance,

Cheers,

Alex

[jim321]

a lot of the time garbled serial problems comes from having the wrong baud rate..

[alexl04]

Problem solved!

Hi jim321 and Didier B,

Many thanks for your swift feedback and pointing me into te right direction! It was indeed a combination of both your help. I knew about the importance of the baudrate setting but I forgot to set it at 4800 on my macbook during checks. Secondly, indeed the wiring was not correct!

I only needed the data output of the GEONAV and the RS422 might indeed not be 1:1 with the old GEONAV. So after some trial and errors this is how it worked:
- Set baudrate at 4800,
- Connect the DATA - Output cable from the Geonav with the DATA + Input cable from the RS422,
- Connect the DATA + Output cable from the Geonav with the DATA - Input cable from the RS422,
- Connect the GROUND wire from the GOENAV with the GROUND wire from the RS422 USB Cable.

Note the swapped + and - which I do not fully understand. Anyhow, for now no time to study this and more important, I'm now able to read the GPS coordinates from the GEONAV on my macbook/ Ipad Pro. 

Openplotter on you PI will do the rest of the magic.

Happy Sailing,

Cheers.