OpenMarine

I am a newbie to this forum. I have configured a Raspberry-Pi 4 to have OpenPlotter installed on it.
It has a usb GPS working already. A usb SDR also up and running. 
I have purchased a usb to RS485 to connect to the accessory cable provided by Uniden.
I have a UM435 vhf radio.
I have attempted to interface the OpenPlotter to the VHF radio.
I have followed a number of tutorials on how to connect and trouble shoot.

Here are the steps taken so far:
1. Updated all software on raspberry and openplotter.
2. Verified the gps and AIS is working on the raspberrry device.
3. Verified the polarity of the 2 wire connector on the USB to RS485.
4. Connected the accessory cable wires required. Green neg date in and Yellow pos data in.
5. Used Serial app on OpenPlotter to recognize and add new usb device. Used the Signal K connection. Set baud rate to 4800. NMEA ID vhfout. Sending RMC,GLL,GNS,GGA, and ZDA. 
6. Implemented the NMEA to NMEA* plugin in to route the GPS info to the vhfout. Restarted SignalK server.
7. Connected accessory cable to VHF radio. 
8. No GPS info appearing on VHF radio as per manual instruction.
Trouble shooting
I used the server log filtering and I am able to see vhfout information streaming by. 
used the terminal and used cat /dev/ttysOP_vhfout nothing showing up.
Is there anymore information I need to post?
Thanks in advance to all.
Kever

Hi Kever:
I have had the same issues:

I have installed a neo 6m GPS module to replace a globalsat GPS puck type GPS antenna. This has been in usage for years. This has been with the intent to eliminate some issues with using a USB interface with my tablet chartplotte (windows). and also to allow a GPS signal to be fed into my new Uniden VHS.
I have valid nmea 0183 sentences being received into my tablet via a usb to ttl adapter, and in parallel to an arduino MCU used for autopilot. Both these "listeners" are fully functional. This working circuit is TTL positive 5v - 2 wire. 


However I have had absolutely no success in getting my VHS to see the same NMEA input.
My next trip to the boat I will try totally removing the green wire and ground wires and measure the signal both connected and disconnected.

I phoned to get support from Uniden and basically they were unable to give any other info other than what is printed in their manual (confusing due to lack of sufficient content)

 I have researched on line re nmea electrical specifications. In overview NMEA is a pretty mixed up scene whereby the various revisions are incompatible, and so devices that were designed for different nmea revisions will not work with one another adaquately. For instance a version  less than version 2 (my Uniden Manual says " in compliance with" version 2) uses a 2 wire data system = data and ground. The VHF uses per nmea version 2,  a 4 wire system = data in plus and neg, and data out plus and neg, with the neg not being neccesariliy the same, or common, with ground or shield. It is totally unclear to me what the VHF expects to see re data volts. It is very clear that most manufacturers do not adhere to the "standard" for instance regarding whether or not the signal goes negative on the start or stop bit etc (at this point it gets over my pay grade!!). For sure my working circuit is TTL positive 5v /0v (TX/RX) while the VHF ( if indeed it is designed  as fully version 2) is pos and neg with regard to each of the in/out pairs and each pair is ungrounded. But what does the RPI need to see? I'm not so sure about this as USB is 4 wire - but with power -/+ and data +/- and is a different protocol. With the rs 485 adapter you are, I think, taking the TTL data (albeit version 2 spec) and converting it to USB. The VHF is expecting the raw signal and the RPI in getting the data signal via adapter does not indicate that the data the VHF sees is indeed valid for its purposes.

I too am trying to get a RPI 4 into my system and am have some substantial issues in getting the serial/AIS configuarations set up properly.

Since you are using a RS 485 interface adapter you are somewhat ahead of me in its usage. I was hoping to use the RPI pins rather than USB. Looking at some of the rs 485 adapters on ebay, it would be good to know which type adapter you have - some seem to be 2 wire while others look like 4 wire.

I had put my RPI aside after getting pretty fraustrated with these issues, but in writing this reply it bring me to look towards abandoning my plan to use the RPI pins and getting some rs 485 adapters . This will not help in getting the VHF to connect.

It would be good to make contact and share any knowledge improvements.

Richard
SV Zolanda

---

heres a suplement to my previous - see

https://www.bb-elec.com/Learning-Center/...ndard.aspx


An extract re volts
"
The EIA RS-485 Specification labels the data wires "A" and "B", but many manufacturers label their wires "+" and "-". In our experience, the "-" wire should be connected to the "A" line, and the "+" wire to the "B" line. Reversing the polarity will not damage a 485 device, but it will not communicate. This said, the rest is easy: always connect A to A and B to B. Signal ground, don't forget it. While a differential signal does not require a signal ground to communicate, the ground wire serves an important purpose. Over a distance of hundreds or thousands of feet there can be very significant differences in the voltage level of "ground." RS-485 networks can typically maintain correct data with a difference of -7 to +12 Volts.
"
NMEA 0183 version 2   specs 5v and remember RPI is a 3.3v device

Richard

(2021-07-06, 09:49 PM)burgoynebc@netscape.net Wrote: [ -> ]Well Richard I am going to attach some screen shots of what I have don so far on the raspberry desktop. Here also is a link to the device I purchased:https://www.amazon.com/JBtek-Converter-Adapter-ch340T-Supported/dp/B00NKAJGZM/ref=pd_bxgy_147_img_2/134-7122820-6842216?_encoding=UTF8&pd_rd_i=B00NKAJGZM&pd_rd_r=10d1afbd-7f1c-11e9-b4c5-ef907af3647f&pd_rd_w=OnLcg&pd_rd_wg=Glz07&pf_rd_p=a2006322-0bc0-4db9-a08e-d168c18ce6f0&pf_rd_r=4TKS8BFKZZ27KYJ19G33&psc=1&refRID=4TKS8BFKZZ27KYJ19G33

The attached picture is from the OpenPlotter/ Raspian desktop. I used cat command at the CLI (Command Line Interface = Terminal) to see if any thing was going on at the usb connections. My GPS showed all kinds of info coming in, my output to the RS485 shows nothing. 
I used the NMEA to NMEA plugin as instructed by the documentation provided by OpenPlotter. I have the GPS giving nmea0183out, and the vhfout set for the RS485. So in theory using Signal K, it should be seeing a vhfout being generated every time nmea0183out send it information.
vhfout is set to send out only RMC,GLL,GNS,GGA, and ZDA. This was all setup in the NMEA to NMEA plugin.
It does all that but nothing arrives at the physical usb port going to the VHF radio.
Hope this helps. 
Kever 

---

This shows that vhfout is filtering and sending out the information that should be going to the VHF radio.

---

(2021-07-07, 01:46 AM)Kever Wrote: [ -> ]This shows that vhfout is filtering and sending out the information that should be going to the VHF radio.

One thought, in the NMEA to NMEA plugin it might make sense to use a different name to nmea0183out. The signalk to nmea app sends data with that label and nmea0183out gets sent out the tcp 10110 connection to opencpn by default as well, good luck with the adapter. If you have a spare arduino you could use it to double check the data is going out, though if it's showing in server-event vhfout it should be.

(2021-07-07, 09:49 AM)PaddyB Wrote: [ -> ]One thought, in the NMEA to NMEA plugin it might make sense to use a different name to nmea0183out. The signalk to nmea app sends data with that label and nmea0183out gets sent out the tcp 10110 connection to opencpn by default as well, good luck with the adapter. If you have a spare arduino you could use it to double check the data is going out, though if it's showing in server-event vhfout  it should be.

THe nmea to nmea allows me to reroute the nmeaout to my own variable with filtering.

(2021-07-08, 02:53 PM)Kever Wrote: [ -> ]

(2021-07-07, 09:49 AM)PaddyB Wrote: [ -> ]One thought, in the NMEA to NMEA plugin it might make sense to use a different name to nmea0183out. The signalk to nmea app sends data with that label and nmea0183out gets sent out the tcp 10110 connection to opencpn by default as well, good luck with the adapter. If you have a spare arduino you could use it to double check the data is going out, though if it's showing in server-event vhfout  it should be.

THe nmea to nmea allows me to reroute the nmeaout to my own variable with filtering.

Other services use the same variable name "nmea0183out" though, it's not your own variable name, anything you send to that will also get sent from tcp 10110. if you want complete control over what goes to the vhf a different variable name would be a good idea.

I have taken the device I purchase, JBtek USB to RS485 Converter Adapter ch340T chip, and tested it on my laptop. It locks the cat /dev/ttyUSB0 output till unplugged. This is probably the problem.
I have ordered the following for it's replacement:https://www.amazon.ca/DTECH-RS485-RS422-Serial-Adapter/dp/B06WGQDV7Z

(2021-07-08, 08:04 PM)Kever Wrote: [ -> ]I have taken the device I purchase, JBtek USB to RS485 Converter Adapter ch340T chip, and tested it on my laptop. It locks the cat /dev/ttyUSB0 output till unplugged. This is probably the problem.
I have ordered the following for it's replacement:https://www.amazon.ca/DTECH-RS485-RS422-Serial-Adapter/dp/B06WGQDV7Z

I have the Dtech one working on my system with a Garmin chartplotter and Raymarine Autopilot.  I did have to connect - to + and vice versa though, but I think that will depend on the VHF

(2021-07-09, 03:44 PM)Techstyle Wrote: [ -> ]

(2021-07-08, 08:04 PM)Kever Wrote: [ -> ]I have taken the device I purchase, JBtek USB to RS485 Converter Adapter ch340T chip, and tested it on my laptop. It locks the cat /dev/ttyUSB0 output till unplugged. This is probably the problem.
I have ordered the following for it's replacement:https://www.amazon.ca/DTECH-RS485-RS422-Serial-Adapter/dp/B06WGQDV7Z

I have the Dtech one working on my system with a Garmin chartplotter and Raymarine Autopilot.  I did have to connect - to + and vice versa though, but I think that will depend on the VHF

Was that specific to send nmea GPS to the VHF radio?

(2021-07-15, 08:25 PM)Kever Wrote: [ -> ]

(2021-07-09, 03:44 PM)Techstyle Wrote: [ -> ]

(2021-07-08, 08:04 PM)Kever Wrote: [ -> ]I have taken the device I purchase, JBtek USB to RS485 Converter Adapter ch340T chip, and tested it on my laptop. It locks the cat /dev/ttyUSB0 output till unplugged. This is probably the problem.
I have ordered the following for it's replacement:https://www.amazon.ca/DTECH-RS485-RS422-Serial-Adapter/dp/B06WGQDV7Z

I have the Dtech one working on my system with a Garmin chartplotter and Raymarine Autopilot.  I did have to connect - to + and vice versa though, but I think that will depend on the VHF

Was that specific to send nmea GPS to the VHF radio?

it seems like manufacturers are not specific about polarity on the NMEA0183 connection so try:
PI            VHF
TX(+) --> RX(+)
TX(-) --> RX(-)
RX(+) --> TX(+)
RX(-) --> TX(-)

if that doesn't work, swap the polarity:
PI            VHF
TX(+) --> RX(-)
TX(-) --> RX(+)
RX(+) --> TX(-)
RX(-) --> TX(+)

this worked for me on both a Raymarine autopilot and a Garmin Chartplotter.