怎么用串口输出输入字符之和

可以使用下面的C++代码实现：

#include <iostream>
#include <Windows.h>

int main()
{
    // 打开串口
    HANDLE hSerial = CreateFileA("COM1", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
    if (hSerial == INVALID_HANDLE_VALUE) {
        std::cerr << "Failed to open serial port!" << std::endl;
        return -1;
    }

    // 配置串口参数
    DCB dcbSerialParams = { 0 };
    dcbSerialParams.DCBlength = sizeof(dcbSerialParams);
    if (!GetCommState(hSerial, &dcbSerialParams)) {
        std::cerr << "Failed to get serial port state!" << std::endl;
        return -1;
    }
    dcbSerialParams.BaudRate = CBR_9600;
    dcbSerialParams.ByteSize = 8;
    dcbSerialParams.StopBits = ONESTOPBIT;
    dcbSerialParams.Parity = NOPARITY;
    if (!SetCommState(hSerial, &dcbSerialParams)) {
        std::cerr << "Failed to set serial port state!" << std::endl;
        return -1;
    }

    // 发送数据并读取返回值
    char sendData[2] = { '1', '2' };  // 发送字符 '1' 和 '2'
    DWORD bytesWritten;
    if (!WriteFile(hSerial, sendData, 2, &bytesWritten, NULL)) {
        std::cerr << "Failed to write to serial port!" << std::endl;
        return -1;
    }

    char recvData[1];  // 接收返回值
    DWORD bytesRead;
    if (!ReadFile(hSerial, recvData, 1, &bytesRead, NULL)) {
        std::cerr << "Failed to read from serial port!" << std::endl;
        return -1;
    }

    // 输出字符之和
    int sum = (int)sendData[0] + (int)sendData[1] + (int)recvData[0];
    std::cout << "Sum: " << sum << std::endl;

    // 关闭串口
    CloseHandle(hSerial);
    return 0;
}

该代码中，首先打开串口 COM1 并配置串口参数，然后发送字符 '1' 和 '2' 并读取返回值，最后计算字符之和并输出。需要注意的是，串口的具体参数可能因设备和场景而异，需要根据实际情况进行调整。