"Title" causes a node-simconnect crash

[evenar]

"Title" causes a node-simconnect crash

[Pomax]

Oh! So if I change the STRINGV back to STRING128, with null, it works!

    handle.addToDataDefinition(
      POSITION_DATA,
      "TITLE",
      null,
      SimConnectDataType.STRING128,
      0,
      SimConnectConstants.UNUSED
    );

[RobsonMi]

Hi, have you tried with STRINGV and readStringV() as per the samples?
https://github.com/EvenAR/node-simconnect/blob/master/samples/typescript/aircraftInformation.ts

[EvenAR]

You're welcome!

I just tested the sample, and it does work as expected (at least on my machine). However, changing SimConnectPeriod.ONCE to something else (like SimConnectPeriod.SECOND) gives me the same exception (28). It looks like STRINGV can only be used with SimConnectPeriod.ONCE.

I think you can close this issue. I will update the sample to use STRING32 and STRING128 right away to avoid future confusion 😃

[Pomax]

I had not, because the MSFS Simvar docs says its unit is "String (max 128 chars)". Are there docs somewhere that explain when node-simconnect needs a StringV type and when it needs String<num>?

[Pomax]

Updated the code to StringV, looks like the same problem (testing this while sitting in-sim with an airplane loaded on the apron):

import {
  open,
  Protocol,
  SimConnectDataType,
  SimConnectPeriod,
  SimConnectConstants,
} from "node-simconnect";

const POSITION_DATA = 1;
const REQUEST_ID_POSITION_DATA = 1;
const EVENT_ID_PAUSE = 1;

open("My app", Protocol.FSX_SP2)
  .then(function ({ recvOpen, handle }) {
    console.log("Connected to", recvOpen.applicationName);

    handle.addToDataDefinition(
      POSITION_DATA,
      "PLANE LATITUDE",
      "degrees",
      SimConnectDataType.FLOAT64,
      0.0,
      SimConnectConstants.UNUSED
    );
    handle.addToDataDefinition(
      POSITION_DATA,
      "PLANE LONGITUDE",
      "degrees",
      SimConnectDataType.FLOAT64,
      0.0,
      SimConnectConstants.UNUSED
    );

    handle.addToDataDefinition(
      POSITION_DATA,
      "TITLE",
      "string",
      SimConnectDataType.STRINGV,
      0.0,
      SimConnectConstants.UNUSED
    );

    handle.requestDataOnSimObject(
      REQUEST_ID_POSITION_DATA,
      POSITION_DATA,
      SimConnectConstants.OBJECT_ID_USER,
      SimConnectPeriod.SECOND,
      0,
      0,
      0,
      0
    );
    handle.subscribeToSystemEvent(EVENT_ID_PAUSE, "Pause");

    handle.on("event", function (recvEvent) {
      switch (recvEvent.eventID) {
        case EVENT_ID_PAUSE:
          console.log(recvEvent.data === 1 ? "Sim paused" : "Sim unpaused");
          break;
      }
    });

    handle.on("simObjectData", function (recvSimObjectData) {
      switch (recvSimObjectData.requestID) {
        case POSITION_DATA:
          console.log({
            latitude: recvSimObjectData.data.readFloat64(),
            longitude: recvSimObjectData.data.readFloat64(),
            title:  recvSimObjectData.data.readStringV(),
          });
          break;
      }
    });
    handle.on("quit", function () {
      console.log("Quit");
    });
  })
  .catch(function (error) {
    console.log("Connection failed:", error);
  });

Error:

D:\temp>node repro.js
Connected to KittyHawk
D:\temp\node_modules\bytebuffer\dist\bytebuffer-node.js:1861
                throw RangeError("Illegal offset: 0 <= "+offset+" (+"+1+") <= "+this.buffer.length);
                ^

RangeError: Illegal offset: 0 <= 44 (+1) <= 44
    at ByteBuffer.module.exports.ByteBufferPrototype.readCString (D:\temp\node_modules\bytebuffer\dist\bytebuffer-node.js:1861:23)
    at makeString (D:\temp\node_modules\node-simconnect\dist\RawBuffer.js:150:24)
    at RawBuffer.readStringV (D:\temp\node_modules\node-simconnect\dist\RawBuffer.js:139:16)
    at SimConnectConnection.<anonymous> (file:///D:/temp/repro.js:69:44)
    at SimConnectConnection.emit (node:events:513:28)
    at SimConnectConnection.emit (D:\temp\node_modules\node-simconnect\dist\SimConnectConnection.js:78:22)
    at SimConnectConnection._handleMessage (D:\temp\node_modules\node-simconnect\dist\SimConnectConnection.js:1031:22)
    at SimConnectSocket.emit (node:events:513:28)
    at addChunk (node:internal/streams/readable:315:12)
    at readableAddChunk (node:internal/streams/readable:289:9)

[EvenAR]

What happens if you replace "string" with "NULL" or null? According to the official docs for SimConnect_AddToDataDefinition, units name should be "NULL" when requesting strings or structures. In the samples I have used null, so perhaps both variants works 🤷

[Pomax]

If I set it to null, the script seems to just "hang", where it logs Connected to KittyHawk and then doesn't generate any output until I kill node. If I try "NULL" or "null", I get the same crash as above.

[EvenAR]

Hmm, ok. There could be a SimConnect exception happening. Do you get anything if you add this?

handle.on("exception", function (ex) {
  console.log(ex);
});

[Pomax]

ooh, you're right: RecvException { exception: 28, sendId: 4, index: 2 }, so it looks like that's SIMCONNECT_EXCEPTION_DEFINITION_ERROR , which is described as

Specifies that there is a problem with a data definition. Currently this is only used if a variable length definition is sent with SimConnect_RequestDataOnSimObject.

though I admit I'm not sure what a variable length definition is in this context.

[EvenAR]

My only guess is that it refers to variable length strings (STRINGV)

Edit: Great! 🙌

[Pomax]

@EvenAR @RobsonMi thanks for the (ridiculously fast! =D) help! Should I close this and file a new issue to update the .ts example(s), or keep this one open?