modbus-connect/dist/function-codes/read-coils.js

Modbus RTU over Web Serial and Node.js SerialPort

"use strict";
var __defProp = Object.defineProperty;
var __getOwnPropDesc = Object.getOwnPropertyDescriptor;
var __getOwnPropNames = Object.getOwnPropertyNames;
var __hasOwnProp = Object.prototype.hasOwnProperty;
var __export = (target, all) => {
  for (var name in all)
    __defProp(target, name, { get: all[name], enumerable: true });
};
var __copyProps = (to, from, except, desc) => {
  if (from && typeof from === "object" || typeof from === "function") {
    for (let key of __getOwnPropNames(from))
      if (!__hasOwnProp.call(to, key) && key !== except)
        __defProp(to, key, { get: () => from[key], enumerable: !(desc = __getOwnPropDesc(from, key)) || desc.enumerable });
  }
  return to;
};
var __toCommonJS = (mod) => __copyProps(__defProp({}, "__esModule", { value: true }), mod);
var read_coils_exports = {};
__export(read_coils_exports, {
  buildReadCoilsRequest: () => buildReadCoilsRequest,
  parseReadCoilsResponse: () => parseReadCoilsResponse
});
module.exports = __toCommonJS(read_coils_exports);
const FUNCTION_CODE = 1;
const MIN_QUANTITY = 1;
const MAX_QUANTITY = 2e3;
const REQUEST_SIZE = 5;
const RESPONSE_HEADER_SIZE = 2;
function buildReadCoilsRequest(startAddress, quantity) {
  if ((quantity | 0) !== quantity || quantity < MIN_QUANTITY || quantity > MAX_QUANTITY) {
    throw new RangeError(`Quantity must be integer ${MIN_QUANTITY}-${MAX_QUANTITY}`);
  }
  const buffer = new ArrayBuffer(REQUEST_SIZE);
  const view = new DataView(buffer);
  view.setUint8(0, FUNCTION_CODE);
  view.setUint16(1, startAddress, false);
  view.setUint16(3, quantity, false);
  return new Uint8Array(buffer);
}
function parseReadCoilsResponse(pdu) {
  if (!(pdu instanceof Uint8Array)) {
    throw new TypeError("PDU must be Uint8Array");
  }
  const pduLength = pdu.length;
  if (pduLength < RESPONSE_HEADER_SIZE) {
    throw new Error(`PDU too short: expected at least ${RESPONSE_HEADER_SIZE} bytes`);
  }
  if (pdu[0] !== FUNCTION_CODE) {
    throw new Error(
      `Invalid function code: expected 0x${FUNCTION_CODE.toString(16)}, got 0x${pdu[0]?.toString(16)}`
    );
  }
  const byteCount = pdu[1];
  const expectedLength = byteCount + RESPONSE_HEADER_SIZE;
  if (pduLength !== expectedLength) {
    throw new Error(`Invalid length: expected ${expectedLength}, got ${pduLength}`);
  }
  const actualBitCount = pdu[3] << 8 | pdu[4];
  if (actualBitCount > byteCount * 8) {
    throw new Error(`Invalid bit count: ${actualBitCount} exceeds byte capacity`);
  }
  const result = new Array(actualBitCount);
  let resultIndex = 0;
  const dataStart = RESPONSE_HEADER_SIZE;
  for (let byteIndex = 0; byteIndex < byteCount; byteIndex++) {
    const byte = pdu[dataStart + byteIndex];
    const maxBit = Math.min(8, actualBitCount - resultIndex);
    for (let bit = 0; bit < maxBit; bit++) {
      result[resultIndex++] = (byte & 1 << bit) !== 0;
    }
  }
  return result;
}
// Annotate the CommonJS export names for ESM import in node:
0 && (module.exports = {
  buildReadCoilsRequest,
  parseReadCoilsResponse
});