@signalk/nmea0183-signalk

A node.js/JavaScript parser of NMEA0183 sentences. Sentences are parsed to Signal K delta format.

Supported sentences

Note: at this time, unknown sentences will be silently discarded.

Custom Sentences

You can add custom sentence parsers via the Signal K Server plugin mechanism. A plugin can register custom parsers by emitting nmea0183sentenceParser PropertyValues with a value that has the properties

sentence: the three letter id of the sentence
parser: a function with the signature ({ id, sentence, parts, tags }, session) => delta

See custom-sentence-plugin for an example.

Usage

JavaScript API

const Parser = require('@signalk/nmea0183-signalk')
const parser = new Parser()

try {
  const delta = parser.parse('$SDDBT,17.0,f,5.1,M,2.8,F*3E')
  if (delta !== null) {
    console.log(`[delta] ${JSON.stringify(delta, null, 2)}`)
  }
}
catch (e) {
  console.error(`[error] ${e.message}`)
}

Command line

In addition to usage in your code, the parser can be used on the command-line if installed globally (npm install --global). This allows you to pipe data from one program into the parser directly, without using a Signal K server. The parser holds no Signal K tree in memory (a big change vs. 1.x), so the output will be stringified Signal K delta messages.

$ echo '$SDDBT,17.0,f,5.1,M,2.8,F*3E' | nmea0183-signalk

NMEA0183v4 tag blocks

This parser has (limited) support of NMEA0183v4 tag blocks (e.g. \s:airmar dst800,c:1438489697*13\$SDDBT,17.0,f,5.1,M,2.8,F*3E).

Example:

const Parser = require('@signalk/nmea0183-signalk')
const parser = new Parser()

try {
  // backslash starts an escape sequence in JavaScript code, so they need to be double in string literals
  const delta = parser.parse('\\s:airmar dst800,c:1438489697*13\\$SDDBT,17.0,f,5.1,M,2.8,F*3E')
  if (delta !== null) {
    console.log(`[delta] ${JSON.stringify(delta, null, 2)}`)
  }
}
catch (e) {
  console.error(`[error] ${e.message}`)
}

Output:

[delta] {
  "updates": [
    {
      "source": {
        "sentence": "DBT",
        "talker": "airmar dst800",
        "type": "NMEA0183"
      },
      "timestamp": "2015-08-02T04:28:17.000Z",
      "values": [
        {
          "path": "environment.depth.belowTransducer",
          "value": 5.1
        }
      ]
    }
  ]
}

Note: at this time, the checksum of the tag block (`c:143848969713`) is not validated.*

License

Copyright 2016/2017 Signal K and Fabian Tollenaar <fabian@signalk.org>.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.