ModbusCRC16校验 示例代码

作者： Herman Ye @Galbot @Auromix
测试环境： Ubuntu20.04
更新日期： 2023/08/30
注₁： @Auromix 是一个机器人爱好者开源组织。
注₂： 本文在更新日期经过测试，确认有效。

笔者出于学习交流目的，
给出以下ModbusCRC16校验常用的四种函数以及完整示例代码：

1.计算CRC

注意： 此处在末尾进行了高低位交换，可根据需求删减代码交换高低位顺序。

unsigned short calculateModbusCRC16(const vector<uint8_t> &data) {int length = data.size();unsigned short CRC = 0xFFFF; // initial valuefor (int i = 0; i < length; i++) {CRC = CRC ^ data[i]; // XOR byte into least sig. byte of crcfor (int j = 0; j < 8; j++) {if (CRC & 1) {CRC >>= 1;CRC ^= 0xA001;} else {CRC >>= 1;}}}unsigned short swappedCRC = ((CRC >> 8) & 0xFF) | ((CRC & 0xFF) << 8);return swappedCRC;
}

2.添加CRC校验位

注意： 此处进行了高低位交换，可根据需求删减代码交换高低位顺序。

void addModbusCRC16(vector<uint8_t> &data) {unsigned short crc = calculateModbusCRC16(data);// Append CRC bytes to the data vectordata.push_back((crc >> 8) & 0xFF);   // MSBdata.push_back(crc & 0xFF);          // LSB}

3.删除CRC校验位

void removeModbusCRC16(vector<uint8_t> &dataWithCRC) {int length = dataWithCRC.size();// Error checkif (length < 2) {cerr << "Invalid data length" << endl;return;}// Delete CRC at the enddataWithCRC.resize(length - 2);
}

4.比较CRC校验位

bool compareModbusCRC16(const vector<uint8_t> &dataWithCRC) {int length = dataWithCRC.size();// Error checkif (length < 2) {cerr << "Invalid data length" << endl;return false;}// Get data without CRCvector<uint8_t> dataWithoutCRC(dataWithCRC.begin(), dataWithCRC.end() - 2);// Calculateunsigned short calculatedCRC = calculateModbusCRC16(dataWithoutCRC);// Get original CRCunsigned short originalCRC = (dataWithCRC[length - 2] << 8) | dataWithCRC[length - 1];return originalCRC == calculatedCRC;
}

5.完整示例代码

#include <iostream>
#include <vector>
#include <iomanip>
using namespace std;unsigned short calculateModbusCRC16(const vector<uint8_t> &data) {int length = data.size();unsigned short CRC = 0xFFFF; // initial valuefor (int i = 0; i < length; i++) {CRC = CRC ^ data[i]; // XOR byte into least sig. byte of crcfor (int j = 0; j < 8; j++) {if (CRC & 1) {CRC >>= 1;CRC ^= 0xA001;} else {CRC >>= 1;}}}unsigned short swappedCRC = ((CRC >> 8) & 0xFF) | ((CRC & 0xFF) << 8);return swappedCRC;
}void addModbusCRC16(vector<uint8_t> &data) {unsigned short crc = calculateModbusCRC16(data);// Append CRC bytes to the data vectordata.push_back((crc >> 8) & 0xFF);   // MSBdata.push_back(crc & 0xFF);          // LSB}void removeModbusCRC16(vector<uint8_t> &dataWithCRC) {int length = dataWithCRC.size();// Error checkif (length < 2) {cerr << "Invalid data length" << endl;return;}// Delete CRC at the enddataWithCRC.resize(length - 2);
}bool compareModbusCRC16(const vector<uint8_t> &dataWithCRC) {int length = dataWithCRC.size();// Error checkif (length < 2) {cerr << "Invalid data length" << endl;return false;}// Get data without CRCvector<uint8_t> dataWithoutCRC(dataWithCRC.begin(), dataWithCRC.end() - 2);// Calculateunsigned short calculatedCRC = calculateModbusCRC16(dataWithoutCRC);// Get original CRCunsigned short originalCRC = (dataWithCRC[length - 2] << 8) | dataWithCRC[length - 1];// Logcout<< "ModbusCRC16 original: "<<hex<< originalCRC<< endl;cout<< "ModbusCRC16 calculated: "<<hex<< calculatedCRC<< endl;return originalCRC == calculatedCRC;
}int main() {// Example data 1vector<uint8_t> deviceData1 = {0x01, 0x10, 0x00, 0x02, 0x00, 0x06, 0x0C, 0x41, 0x20,0x00, 0x00, 0x42, 0xC8, 0x00, 0x00, 0x42, 0x48, 0x00, 0x00,0x84, 0xC1}; // Example CRC: 0x84, 0xC1// Print original datacout << "Original data 1: ";for (uint8_t byte : deviceData1) {cout << hex << uppercase << setw(2) << setfill('0') << (int)byte << " ";}cout << endl;bool comparedResult=compareModbusCRC16(deviceData1);if (comparedResult)cout<<"Compared result: "<<"TRUE"<<endl;elsecout<<"Compared result: "<<"FALSE"<<endl;// Example data 2cout<<endl;vector<uint8_t> deviceData2 = {0x01, 0x06, 0x00, 0x00, 0x01, 0x02, 0x02};// Example CRC: 0xDA, 0xC7cout << "Original data 2: ";for (uint8_t byte : deviceData2) {cout << hex << uppercase << setw(2) << setfill('0') << (int)byte << " ";}cout << endl;// Add CRC and print modified dataaddModbusCRC16(deviceData2);cout << "Add CRC to original data 2: ";for (uint8_t byte : deviceData2) {cout << hex << uppercase << setw(2) << setfill('0') << (int)byte << " ";}cout << endl;// Remove CRC from dataremoveModbusCRC16(deviceData2);cout << "Remove CRC from modified data 2: ";for (uint8_t byte : deviceData2) {cout << hex << uppercase << setw(2) << setfill('0') << (int)byte << " ";}cout << endl;	return 0;
}