knx/src/dptlib/dpt4.js

KNXnet/IP protocol implementation for Node(>=6.x)

/**
 * knx.js - a KNX protocol stack in pure Javascript
 * (C) 2016-2018 Elias Karakoulakis
 */

const log = require('log-driver').logger;

//
// DPT4: 8-bit character
//
exports.formatAPDU = (value) => {
  if (value == null) return log.warn('DPT4: cannot write null value');

  if (typeof value !== 'string')
    return log.warn('DPT4: Must supply a character or string');

  const apdu_data = value.charCodeAt(0);
  if (apdu_data > 255) return log.warn('DPT4: must supply an ASCII character');

  return Buffer.from([apdu_data]);
};

exports.fromBuffer = (buf) => {
  if (buf.length != 1) return log.warn('DPT4: Buffer should be 1 byte long');

  return String.fromCharCode(buf[0]);
};

exports.basetype = {
  bitlength: 8,
  valuetype: 'basic',
  desc: '8-bit character',
};

exports.subtypes = {
  // 4.001 character (ASCII)
  '001': {
    name: 'DPT_Char_ASCII',
    desc: 'ASCII character (0-127)',
    range: [0, 127],
    use: 'G',
  },
  // 4.002 character (ISO-8859-1)
  '002': {
    name: 'DPT_Char_8859_1',
    desc: 'ISO-8859-1 character (0..255)',
    use: 'G',
  },
};