modbus-connect/function-codes/SGM130/write-device-comment.js

Modbus RTU over Web Serial and Node.js SerialPort

// function-codes/SGM130/write-device-comment.js

const { FUNCTION_CODES } = require('../../constants/constants.js');
const { allocUint8Array, isUint8Array } = require('../../utils/utils.js');

/** Таблица кодов символов по спецификации */
const CHAR_TO_CODE = {
  ' ': 0, '0': 1, '1': 2, '2': 3, '3': 4, '4': 5, '5': 6, '6': 7, '7': 8, '8': 9, '9': 10,
  'A': 11, 'B': 12, 'C': 13, 'D': 14, 'E': 15, 'F': 16, 'G': 17, 'H': 18, 'I': 19, 'J': 20,
  'K': 21, 'L': 22, 'M': 23, 'N': 24, 'O': 25, 'P': 26, 'Q': 27, 'R': 28, 'S': 29, 'T': 30,
  'U': 31, 'V': 32, 'X': 33, 'Y': 34, 'Z': 35,
  'А': 37, 'Б': 38, 'В': 39, 'Г': 40, 'Д': 41, 'Е': 42, 'Ж': 43, 'З': 44, 'И': 45, 'Й': 46,
  'К': 47, 'Л': 48, 'М': 49, 'Н': 50, 'О': 51, 'П': 52, 'Р': 53, 'С': 54, 'Т': 55, 'У': 56,
  'Ф': 57, 'Х': 58, 'Ц': 59, 'Ч': 60, 'Ш': 61, 'Щ': 62, 'Ъ': 63, 'Ы': 64, 'Ь': 65, 'Э': 66,
  'Ю': 67, 'Я': 68
};

/**
 * Создаёт PDU-запрос для записи комментария устройства
 * @param {number} channel - номер канала (0–255)
 * @param {string} comment - строка комментария (макс. 16 символов)
 * @returns {Uint8Array}
 */
function buildWriteDeviceCommentRequest(channel, comment) {
  if (channel < 0 || channel > 255) {
    throw new RangeError('Invalid channel number');
  }

  if (typeof comment !== 'string') {
    throw new TypeError('Comment must be a string');
  }

  const trimmed = comment.trim().toUpperCase();
  if (trimmed.length > 16) {
    throw new Error('Comment is too long (max 16 characters)');
  }

  const encoded = [];
  for (const ch of trimmed) {
    const code = CHAR_TO_CODE[ch];
    if (code === undefined) {
      throw new Error(`Unsupported character: "${ch}"`);
    }
    encoded.push(code);
  }

  // Дополняем до 16 байт кодом пробела (0)
  while (encoded.length < 16) {
    encoded.push(0);
  }

  const pdu = allocUint8Array(3 + 16);
  pdu[0] = FUNCTION_CODES.WRITE_DEVICE_COMMENT;
  pdu[1] = channel;
  pdu[2] = 16;
  for (let i = 0; i < 16; i++) {
    pdu[3 + i] = encoded[i];
  }

  return pdu;
}

/**
 * Парсит ответ устройства на запись комментария
 * @param {Uint8Array} pdu
 * @returns {{ channel: number, length: number }}
 */
function parseWriteDeviceCommentResponse(pdu) {
  if (!isUint8Array(pdu)) {
    throw new TypeError('PDU must be Uint8Array');
  }

  const fc = FUNCTION_CODES.WRITE_DEVICE_COMMENT;

  if (pdu[0] !== fc) {
    throw new Error(`Invalid function code: expected 0x${fc.toString(16)}, got 0x${pdu[0].toString(16)}`);
  }

  const channel = pdu[1];
  const length = pdu[2];

  if (length !== 16) {
    throw new Error(`Invalid string length: expected 16, got ${length}`);
  }

  return { channel, length };
}

module.exports = {
  buildWriteDeviceCommentRequest,
  parseWriteDeviceCommentResponse
}