How to use Send NMEA2000 to output PGN 127505 (Fluid Level)

General
1

I am new to Signal-K and Node-Red, so please excuse me if this is obvious to more experienced users. I have a Victron Cerbo running Signal-K and Node-Red. I have ultrasonic fluid transducers that provide highly varying level readings. I want to smooth the data and send out a level of the data over the past 30 seconds using a different instance. So here's what I've done:

Subscribe to tanks.freshWater.1.currentLevel (which outputs every 2.5 seconds)
Feed that into a smooth function which outputs every 12 results (every 30 seconds)
Feed the output of the smooth into a function that contains:

const pgn = {
  "pgn": 127505,
  "Instance": 102,
  "Type": "Fresh Water",
  "Level": Number(level),
  "Capacity": 0.1
}
msg.payload = pgn;
return msg;

This msg.payload is the input for signalk-send-nmea2000. However, I don't see a tanks.freshWater.102 appear.

What am I doing wrong? I'm guessing that I have the wrong Type, but can't find where TANK_TYPE is defined.

Here's the definition of PGN 127505:

     127505,
     PACKET_COMPLETE,
     PACKET_SINGLE,
     {SIMPLE_FIELD(PK("Instance"), 4),
      LOOKUP_FIELD("Type", 4, TANK_TYPE),
      PERCENTAGE_I16_FIELD("Level"),
      VOLUME_UFIX32_DL_FIELD("Capacity"),
      RESERVED_FIELD(BYTES(1)),
      END_OF_FIELDS},
     .priority = 6,
     .url      = "https://web.archive.org/web/20060511065306/http://www.maretron.com/support/manuals/TLA100UM_1.2.pdf",
     .interval = 2500}```
2

I am not entirely sure what you are asking about.

If you feed the output of your function into a debug node do you see what you expect?

Is that the complete function you have posted? If so then level is undefined and that should show with a red line under it to tell you there is a problem
image

3

Sorry, I thought that I had copied the entire function code. Here's the missing line at the top:

var level = msg.payload;

I do feed it into a debug node, and the output of the debug node is precisely as expected.

Once again, I suspect that my TANK_TYPE is in error, but that may be completely wrong. How do I find out what valid TANK_TYPE values are? Alternately, does signalk-send-nmea2000 return an error that I can view?

4

OK, in which case there wasn't any need to post the function, you could just have shown us what comes out of it.

I think you will need someone who knows about signalK and the particular node you are using.