question

@JohnJayMack If you have a look at the manual, GPS over TCP is not supported. It supports GPS over NMEA 2000 or via a USB GPS receiver. You might want to take a look at this post, but it uses UDP rather than TCP. Works well as I myself used it for a while. However a USB GPS costs very little and will just work. Anything you modify on the VenusOS to get this working will need to be re-done after any firmware upgrades.

I am aware that I can buy a USB GPS module, connect it to the CERBO GX, which is secured deep within the vehicle, and get a GPS output if the USB GPS module can actually receive the GPS signals. I also realize that the best GPS availability comes from an external antenna with an unobstructed view of the sky.

I have looked at the documentation for the Victron GPS Node Red input module. Documentation states:

"

GPS information can be obtained with this node. For an example usage see the location based scheduling example.

Altitude (m), dbus path: /Altitude, type float
Course (Deg), dbus path: /Course, type float
Fix, dbus path: /Fix, type integer
Number of satellites, dbus path: /NrOfSatellites, type integer
Latitude (LAT), dbus path: /Position/Latitude, type float
Longitude (LNG), dbus path: /Position/Longitude, type float
Speed (m/s), dbus path: /Speed, type float"

I am not an accomplished programmer. That being said, it appears that the NMEA $GP CSV sentences are being parsed to fill in the dbus path variables.

There is a NODE RED parser module called "nmea" that accepts a TCP input such as a $GPRMC and $GPGGA and outputs as follows:

msg.payload : Object

objectsentence: "RMC"type: "nav-info"timestamp: "212705.00"status: "valid"lat: 38.76796805latPole: "N"lon: -120.61720815lonPole: "W"speedKnots: 0trackTrue: 190.3date: "130423"variation: 15.4variationPole: "E"talker_id: "GP"dateTime: "2023-04-13T21:27:05.000Z", &

msg.payload : Object

objectsentence: "GGA"type: "fix"timestamp: "212715.00"lat: 38.76796797latPole: "N"lon: -120.6172085lonPole: "W"fixType: "fix"numSat: 9horDilution: 0.8alt: 1091.3altUnit: "M"geoidalSep: -23geoidalSepUnit: "M"differentialAge: 0differentialRefStn: ""talker_id: "GP"

It appears that ALL of the information required by the Victron GPS module is contained in the two nmea sentences GPRMC and GPGGA. The disconnect is taking the information available in the NMEA sentence and writing it to the dbus path: ?variable name.

Is there a NODE RED Node available to 1) read the data stored in the variable on the dbus, and to 2) write to the same variable data? It appears that the Victron GPS node is looking at the dbus path and variables. What would be required to write information to those same variables?

I have been doing some research and I believe I know what might work. Whether I can develop the programming skills is yet to be determined.

I am using Node Red modules and think that this approach might be viable.

First, the router that I have, a Pepwave, outputs a steady stream of nmea sentences at TCP 192.168.50.1:60660. Using the tcp in node, I get the sentences. I need data from two different sentences: GPRMC and GPGGA. I run the output through a switch node to split the two sentences into two paths. Then I run each message through a nema parser node. This gives me the two different message payload objects: (I have put the variable that the Victron GPS module is looking for out to the right Bold Underline.

RMC msg.payload : Object

objectsentence: "RMC"

type: "nav-info"

timestamp: "025109.00"

status: "valid"

lat: 38.7679971 Latitude (LAT)float

atPole: "N"

lon: -120.61722535 Longitude (LNG)float

lonPole: "W"

speedKnots: 0 Speed (m/s)float

trackTrue: 223 Course (Deg)float

date: "140423"

variation: 15.4

variationPole: "E"

talker_id: "GP"

dateTime: "2023-04-14T02:51:09.000Z"

and

msg.payload : Object

objectsentence: "GGA"

type: "fix" Fixinteger

timestamp: "025119.00"

lat: 38.76799702 Latitude (LAT)float

latPole: "N"

lon: -120.6172254 Longitude (LNG)float

lonPole: "W"

fixType: "fix"

numSat: 7 Number of satellitesinteger

horDilution: 1.6

alt: 1095.9 Altitude (m)float

altUnit: "M"

geoidalSep: -23

geoidalSepUnit: "M"

differentialAge: 0

differentialRefStn: ""

talker_id: "GP"

The GPS input node looks for the following:

Altitude (m)float

Dbus path: /Altitude

Course (Deg)float

Dbus path: /Course

Fixinteger

Dbus path: /Fix

Number of satellitesinteger

Dbus path: /NrOfSatellites

Latitude (LAT)float

Dbus path: /Position/Latitude

Longitude (LNG)float

Dbus path: /Position/Longitude

Speed (m/s)float

Dbus path: /Speed

Would it be possible to modify the Victron GPS module to directly accept the information parsed from the tcp nmea sentences? I could not find the Victron GPS source code, so I cannot look at it to see what might be changed. And quite honestly, I know that at this time, I would have to learn the programming language.

So to Victron, how do you go about getting the source programming to take a look at the existing code to see if it could be modified?

Thanks,

Jay

Hi! I reread the thread linked to by Mbath above, and there are many good suggestions in there.

I have nothing to add to what is already there. Also perhaps best to keep the discussion there and in one place?