求助：如何用C#通过串口将电子秤重量读取到文本框

问题描述 #

我正尝试仅将电子秤的重量数据读取到应用程序中，试了一些代码但都无效。我需要仅将重量数据显示到文本框中，用于POS程序。试过多种代码片段均无法实现需求。

原使用代码：

namespace WS_POS
{
    public partial class Test1 : XtraForm
    {
        static SerialPort _serialPort;        
        private const int BaudRate = 9600;

        public Test1()
        {
            InitializeComponent();
        }

        private void Test1_Load(object sender, EventArgs e)
        {
            string[] portNames = SerialPort.GetPortNames();     

            foreach (var portName in portNames)
            {
                comboBox1.Items.Add(portName);                  
            }

            comboBox1.SelectedIndex = 0;
        }

        private delegate void Closure();

        private void SerialPortOnDataReceived(object sender, SerialDataReceivedEventArgs serialDataReceivedEventArgs)
        {
            if (InvokeRequired)     
                BeginInvoke(new Closure(() => { SerialPortOnDataReceived(sender, serialDataReceivedEventArgs); }));    
            else
            {
                int dataLength = _serialPort.BytesToRead;
                byte[] data = new byte[dataLength];
                int nbrDataRead = _serialPort.Read(data, 0, dataLength);

                if (nbrDataRead == 0)
                    return;

                string str = System.Text.Encoding.UTF8.GetString(data);
                T2.Text = str.ToString();
            }
        }

        private void simpleButton1_Click(object sender, EventArgs e)
        {
            if (_serialPort != null && _serialPort.IsOpen)
                _serialPort.Close();

            if (_serialPort != null)
                _serialPort.Dispose();
   
            _serialPort = new SerialPort(comboBox1.Text, BaudRate, Parity.None, 8, StopBits.One);       //<-- Creates new SerialPort using the name selected in the combobox
            _serialPort.DataReceived += SerialPortOnDataReceived;       //<-- this event happens everytime when new data is received by the ComPort
            _serialPort.Open();     //<-- make the comport listen
            T1.Text = "Listening on " + _serialPort.PortName + "...\r\n";
        }
    }
}

解决方案 #

原代码核心问题是未处理串口数据的分段接收，电子秤输出的重量通常是带格式的完整帧（如以\r\n结尾），且包含非重量字符。以下是修改后的代码，解决数据拼接、格式解析问题：

namespace WS_POS
{
    public partial class Test1 : XtraForm
    {
        static SerialPort _serialPort;        
        private const int BaudRate = 9600;
        // 缓存串口分段接收的数据
        private string _receivedBuffer = string.Empty;
        // 电子秤帧结束符（根据设备手册调整，常见为\r\n）
        private const string FrameTerminator = "\r\n";

        public Test1()
        {
            InitializeComponent();
        }

        private void Test1_Load(object sender, EventArgs e)
        {
            string[] portNames = SerialPort.GetPortNames();     
            foreach (var portName in portNames)
            {
                comboBox1.Items.Add(portName);                  
            }
            comboBox1.SelectedIndex = 0;
        }

        // 更新UI的委托
        private delegate void UpdateWeightDelegate(string weight);

        private void SerialPortOnDataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            try
            {
                // 读取当前串口缓冲区所有数据
                string newData = _serialPort.ReadExisting();
                _receivedBuffer += newData;

                // 处理所有已收到的完整帧
                while (_receivedBuffer.Contains(FrameTerminator))
                {
                    int terminatorIndex = _receivedBuffer.IndexOf(FrameTerminator);
                    string fullFrame = _receivedBuffer.Substring(0, terminatorIndex);
                    // 移除已处理的帧，更新缓冲区
                    _receivedBuffer = _receivedBuffer.Substring(terminatorIndex + FrameTerminator.Length);

                    // 提取纯重量数字（含小数点）
                    string weightStr = new string(fullFrame.Where(c => char.IsDigit(c) || c == '.').ToArray());
                    if (!string.IsNullOrEmpty(weightStr))
                    {
                        // 跨线程安全更新UI
                        T2.Invoke(new UpdateWeightDelegate(UpdateWeightDisplay), weightStr);
                    }
                }
            }
            catch (Exception ex)
            {
                // 捕获异常并写入日志框
                T1.Invoke(new Action(() => T1.Text += $"Error: {ex.Message}\r\n"));
            }
        }

        // 更新重量显示
        private void UpdateWeightDisplay(string weight)
        {
            T2.Text = weight;
            // 可选：添加单位，比如 T2.Text = $"{weight} kg";
        }

        private void simpleButton1_Click(object sender, EventArgs e)
        {
            try
            {
                if (_serialPort != null && _serialPort.IsOpen)
                {
                    _serialPort.Close();
                    _serialPort.Dispose();
                }

                _serialPort = new SerialPort(comboBox1.Text, BaudRate, Parity.None, 8, StopBits.One);
                _serialPort.DataReceived += SerialPortOnDataReceived;
                _serialPort.NewLine = FrameTerminator;
                _serialPort.Open();

                T1.Text = $"Listening on {_serialPort.PortName}...\r\n";
                _receivedBuffer = string.Empty; // 重置缓冲区
            }
            catch (Exception ex)
            {
                T1.Text += $"Failed to open port: {ex.Message}\r\n";
            }
        }
    }
}

关键修改说明 #

• 数据缓存与帧解析：用_receivedBuffer缓存分段数据，直到检测到结束符，确保处理完整的重量帧。
• 重量提取逻辑：过滤字符提取纯数字（含小数点），适配常见电子秤输出格式（如WEIGHT: 12.34 kg\r\n）。
• 线程安全优化：用Invoke安全更新UI，避免跨线程操作异常。
• 异常处理：添加捕获机制，避免串口操作异常导致程序崩溃，便于调试。

注意：若电子秤输出格式特殊（如固定长度、特定前缀），需根据设备手册调整FrameTerminator和重量提取逻辑。

内容的提问来源于stack exchange，提问作者Ayman Alhaj