C#时间戳准换成byte发送到下位机部分代码

public void TestA()
{
int time = 1658310821;

        string str = time.ToString("X4");
        byte[] testb = strToHexByte(str);
    }
    /// <summary>
    /// 16进制字符串转换成16进制byte数组
    /// </summary>
    /// <param name="hexString"></param>
    /// <returns></returns>
    public  byte[] strToHexByte(string hexString)
    {
        hexString = hexString.Replace(":", "");
        if ((hexString.Length % 2) != 0)
            hexString += " ";
        byte[] returnBytes = new byte[hexString.Length / 2];
        for (int i = 0; i < returnBytes.Length; i++)
            returnBytes[i] = Convert.ToByte(hexString.Substring(i * 2, 2), 16);
        return returnBytes;
    }