WPF + ADS 通信：心跳检测与指数退避自动重连工程实现

// IAdsService.cs — 定义通信接口，便于 Mock 测试
public interface IAdsService
{
    bool IsConnected { get; }
    event Action<bool> ConnectionChanged;
    Task<T> ReadAsync<T>(string symbolName);
    Task WriteAsync<T>(string symbolName, T value);
}

// AdsService.cs — 指数退避重连（1→2→4→8→15→30s）
private int[] _backoffSeconds = { 1, 2, 4, 8, 15, 30 };
private int  _retryIndex = 0;

private async Task HeartbeatLoopAsync(CancellationToken ct)
{
    while (!ct.IsCancellationRequested)
    {
        await Task.Delay(1000, ct);
        try
        {
            var state = await _client.ReadStateAsync();
            if (state.AdsState != AdsState.Run)
                throw new AdsException("PLC not in Run state");
            _retryIndex = 0;          // 重置退避计数
            SetConnected(true);
        }
        catch
        {
            SetConnected(false);
            await ReconnectWithBackoffAsync(ct);
        }
    }
}

private async Task ReconnectWithBackoffAsync(CancellationToken ct)
{
    var wait = _backoffSeconds[
        Math.Min(_retryIndex, _backoffSeconds.Length - 1)];
    _retryIndex++;
    await Task.Delay(wait * 1000, ct);
    try
    {
        _client.Disconnect();
        _client.Connect(_amsNetId, _port);
        SetConnected(true);
        _retryIndex = 0;
    }
    catch { /* 继续下一轮退避 */ }
}

// MainViewModel.cs — 连接状态绑定到 UI
public string ConnectionStatus =>
    _adsService.IsConnected ? "● 在线" : "○ 离线";

public string StatusColor =>
    _adsService.IsConnected ? "#2e9e5b" : "#cc3333";

// 构造函数中订阅事件，通过 Dispatcher 回到 UI 线程
_adsService.ConnectionChanged += isConnected =>
    Application.Current.Dispatcher.Invoke(() =>
    {
        OnPropertyChanged(nameof(ConnectionStatus));
        OnPropertyChanged(nameof(StatusColor));
    });