1.CRC校验

/*计算CRC-16/MODBUS校验位高低位*/
function calculateCRC16Modbus(dataHexString) {const dataBytes = [];for (let i = 0; i < dataHexString.length; i += 2) {dataBytes.push(parseInt(dataHexString.substr(i, 2), 16));}let crc = 0xFFFF;const polynomial = 0xA001; // This is the polynomial x^16 + x^15 + x^2 + 1for (const byte of dataBytes) {crc ^= byte;for (let i = 0; i < 8; i++) {if (crc & 0x0001) {crc = ((crc >> 1) ^ polynomial) & 0xFFFF;} else {crc >>= 1;}}}crc = pad(crc.toString(16).toUpperCase(),4);//补0(不然会出八阿哥)let crcArr = new Array(2)console.log('crc='+crc)crcArr[0] = crc.substring(2, 4)crcArr[1] = crc.substring(0, 2)let code = crcArr[0] + crcArr[1]return code
}

2.异或校验

// 生成校验码
function genCheckCode(msgBodyCode) {let firstByte = null;for (let i = 0; i < msgBodyCode.length; i = i + 2) {const curCode = '0x' + msgBodyCode.substring(i, i + 2);if (i == 0) {firstByte = curCode} else {firstByte = firstByte ^ curCode}}firstByte = parseInt(firstByte)const codePad = pad(firstByte.toString(16), 2)console.log('校验码==' + codePad)return codePad;
}

3.pad 左侧补0方法

// 左侧补齐0
function pad(str, max) {str = str.toString();return str.length < max ? pad("0" + str, max) : str;
}

4.16进制和float（4字节）互转

/*4字节byte十六进制转浮点数      解析   */
function hex2float(hexString, precision) {//hex2float('EC519A44', 2))precision = parseInt(precision)if (isNaN(precision) || precision < 0) {precision = 2}// 高低位转换const byteArray = [];for (let i = 0; i < hexString.length; i += 2) {byteArray.unshift(hexString.substr(i, 2));}// 创建一个包含十六进制数的 ArrayBufferconst hexValue = '0x' + byteArray.join('');const buffer = new ArrayBuffer(4);const dataView = new DataView(buffer);dataView.setUint32(0, hexValue, false);// 从 DataView 中读取浮点数const floatValue = dataView.getFloat32(0, false);return floatValue.toFixed(precision);
}/*浮点数转4字节十六进制      发送*/
function float2hex(floatNumber) {// 创建一个 4 字节的 ArrayBufferconst buffer = new ArrayBuffer(4);// 使用 DataView 来操作 ArrayBufferconst dataView = new DataView(buffer);// 将浮点数写入到 DataView 中dataView.setFloat32(0, floatNumber, false); // 第二个参数是偏移量，false 表示使用大端字节序// 从 DataView 中读取十六进制表示const hexString = dataView.getUint32(0, false).toString(16).toUpperCase();// 高低位转换const byteArray = [];for (let i = 0; i < hexString.length; i += 2) {byteArray.unshift(hexString.substr(i, 2));}return byteArray.join('');
}