diff --git a/DentistryHandpieces/MainWindowViewModel.cs b/DentistryHandpieces/MainWindowViewModel.cs
index 1258a91..96fe30f 100644
--- a/DentistryHandpieces/MainWindowViewModel.cs
+++ b/DentistryHandpieces/MainWindowViewModel.cs
@@ -103,6 +103,7 @@ public sealed class MainWindowViewModel : ObservableObject
     private const double MinimumTorqueChangeThreshold = 0.05;
     private const string TorqueUnit = "mN.m";
     private static readonly TimeSpan RealtimeRefreshInterval = TimeSpan.FromMilliseconds(100);
+    private static readonly TimeSpan RealtimeDataFreshnessTimeout = TimeSpan.FromSeconds(3);
     private static readonly TimeSpan SnapshotInterval = TimeSpan.FromSeconds(5);
     private static readonly TimeSpan NoLoadCaptureDuration = TimeSpan.FromSeconds(3);
     private static readonly TimeSpan SpeedTorqueStartConfirmationTimeout = TimeSpan.FromSeconds(5);
@@ -220,6 +221,7 @@ public sealed class MainWindowViewModel : ObservableObject
     private bool _isReadingParameterConfig;
     private bool _hasLoadedParameterConfigFromPlc;
     private bool _lastRealtimeReadFailed;
+    private DateTime _lastSuccessfulRealtimeReadAt = DateTime.MinValue;
     private bool _isAutoStoppingDisplacement;
     private bool _isAutoStoppingSpeedTorque;
     private bool _isApplyingParameterConfigToInputs;
@@ -752,11 +754,10 @@ public sealed class MainWindowViewModel : ObservableObject
         try
         {
             PlcConnectionConfig config = _parameterConfig.ToPlcConnectionConfig();
-            Task<IReadOnlyDictionary<ushort, float>> registerReadTask =
-                _plcRegisterService.ReadFloatValuesAsync(config, RealtimeRegisterAddresses);
-            Task<IReadOnlyDictionary<ushort, bool>> coilReadTask =
-                _plcCoilService.ReadCoilValuesAsync(config, RealtimeCoilAddresses);
-            IReadOnlyDictionary<ushort, float> values = await registerReadTask;
+            IReadOnlyDictionary<ushort, float> values =
+                await _plcRegisterService.ReadFloatValuesAsync(config, RealtimeRegisterAddresses);
+            IReadOnlyDictionary<ushort, bool> coilValues =
+                await _plcCoilService.ReadCoilValuesAsync(config, RealtimeCoilAddresses);
 
             double dialIndicator = ReadFloatValue(values, DialIndicatorRegister, "千分表显示");
             double axialForce = ReadFloatValue(values, AxialForceDisplayRegister, "轴向力显示");
@@ -788,12 +789,12 @@ public sealed class MainWindowViewModel : ObservableObject
             UpdateSpeedTorqueDisplay();
             UpdateNoLoadSpeedDisplay();
 
-            IReadOnlyDictionary<ushort, bool> coilValues = await coilReadTask;
             ApplyResetCoilValues(coilValues);
             ApplyAxialForceModeState(ReadCoilValue(coilValues, AxialForceModeCoil));
             bool isVentValveOpen = ReadCoilValue(coilValues, VentValveCoil);
             VentValveButtonText = isVentValveOpen ? "关闭气阀" : "通气阀";
 
+            _lastSuccessfulRealtimeReadAt = DateTime.Now;
             CaptureRealtimeSample(dialIndicator, coilValues);
             FinalizeNoLoadSpeedRunIfDue();
             QueueSnapshotIfDue();
@@ -837,7 +838,7 @@ public sealed class MainWindowViewModel : ObservableObject
         {
             if (!_lastRealtimeReadFailed)
             {
-                StatusText = $"实时数据读取失败：{OperatorMessageFormatter.FromException(ex)}";
+                StatusText = $"实时数据读取失败，当前读数为上次有效值：{OperatorMessageFormatter.FromException(ex)}";
                 _lastRealtimeReadFailed = true;
                 Log.Warning(ex, "PLC实时数据读取失败，后续相同故障将等待恢复后再记录");
             }
@@ -2433,6 +2434,12 @@ public sealed class MainWindowViewModel : ObservableObject
             return;
         }
 
+        if (!TryGetRealtimeSpeed(out _))
+        {
+            StatusText = "实时数据未更新，已阻止空载转速记录。";
+            return;
+        }
+
         try
         {
             await _plcCoilService.WriteCoilAsync(
@@ -3089,13 +3096,13 @@ public sealed class MainWindowViewModel : ObservableObject
     private bool TryGetDialValue(out double value)
     {
         value = _dialIndicator;
-        return true;
+        return HasFreshRealtimeData() && double.IsFinite(value);
     }
 
     private bool TryGetAxialForceValue(out double value)
     {
         value = _axialForce;
-        return true;
+        return HasFreshRealtimeData() && double.IsFinite(value);
     }
 
     private void UpdateRealtimeSpeedFromInput()
@@ -3244,13 +3251,19 @@ public sealed class MainWindowViewModel : ObservableObject
     private bool TryGetRealtimeSpeed(out double value)
     {
         value = _realtimeSpeed;
-        return true;
+        return HasFreshRealtimeData() && double.IsFinite(value);
     }
 
     private bool TryGetRealtimeTorque(out double value)
     {
         value = _realtimeTorque;
-        return true;
+        return HasFreshRealtimeData() && double.IsFinite(value);
+    }
+
+    private bool HasFreshRealtimeData()
+    {
+        return _lastSuccessfulRealtimeReadAt != DateTime.MinValue
+            && DateTime.Now - _lastSuccessfulRealtimeReadAt <= RealtimeDataFreshnessTimeout;
     }
 
     private void ApplyResetCoilValues(IReadOnlyDictionary<ushort, bool> coilValues)
@@ -3483,7 +3496,14 @@ public sealed class MainWindowViewModel : ObservableObject
 
     private int GetTorqueSampleLimit()
     {
-        return MaxTorqueSampleCount;
+        if (_parameterConfig.TorqueHoldTime <= 0)
+        {
+            return MaxTorqueSampleCount;
+        }
+
+        int requiredSamples = (int)Math.Ceiling(
+            _parameterConfig.TorqueHoldTime / RealtimeRefreshInterval.TotalSeconds) + 2;
+        return Math.Max(MaxTorqueSampleCount, requiredSamples);
     }
 
     private void CaptureRealtimeSample(double dialIndicator, IReadOnlyDictionary<ushort, bool> coilValues)
diff --git a/DentistryHandpieces/ModbusTcpPlcCoilService.cs b/DentistryHandpieces/ModbusTcpPlcCoilService.cs
index b53285c..d9de3c3 100644
--- a/DentistryHandpieces/ModbusTcpPlcCoilService.cs
+++ b/DentistryHandpieces/ModbusTcpPlcCoilService.cs
@@ -34,6 +34,7 @@ public interface IPlcRegisterService
 public sealed class ModbusTcpPlcCoilService : IPlcCoilService, IPlcRegisterService
 {
     private readonly object _transactionLock = new();
+    private readonly SemaphoreSlim _transportLock = new(1, 1);
     private ushort _transactionId;
 
     public async Task PulseCoilAsync(PlcConnectionConfig config, ushort coilAddress, CancellationToken cancellationToken = default)
@@ -94,10 +95,16 @@ public sealed class ModbusTcpPlcCoilService : IPlcCoilService, IPlcRegisterServi
         }
 
         IReadOnlyList<RegisterReadGroup> groups = CreateRegisterReadGroups(registerAddresses);
-        Task<ushort[]>[] readTasks = groups
-            .Select(group => ReadHoldingRegistersAsync(config, group.StartAddress, group.RegisterCount, cancellationToken))
-            .ToArray();
-        ushort[][] groupRegisters = await Task.WhenAll(readTasks);
+        var groupRegisters = new ushort[groups.Count][];
+        for (int groupIndex = 0; groupIndex < groups.Count; groupIndex++)
+        {
+            RegisterReadGroup group = groups[groupIndex];
+            groupRegisters[groupIndex] = await ReadHoldingRegistersAsync(
+                config,
+                group.StartAddress,
+                group.RegisterCount,
+                cancellationToken);
+        }
 
         var values = new Dictionary<ushort, float>();
         for (int groupIndex = 0; groupIndex < groups.Count; groupIndex++)
@@ -199,183 +206,235 @@ public sealed class ModbusTcpPlcCoilService : IPlcCoilService, IPlcRegisterServi
 
     private async Task WriteSingleCoilAsync(PlcConnectionConfig config, ushort coilAddress, bool value, CancellationToken cancellationToken)
     {
-        using var client = new TcpClient();
-        using var timeoutCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
-        timeoutCts.CancelAfter(TimeSpan.FromMilliseconds(config.TimeoutMilliseconds));
-
-        await client.ConnectAsync(config.IpAddress, config.Port, timeoutCts.Token);
-        await using NetworkStream stream = client.GetStream();
-
-        ushort transactionId = NextTransactionId();
-        byte[] request = BuildWriteSingleCoilRequest(transactionId, config.UnitId, coilAddress, value);
-        await stream.WriteAsync(request, timeoutCts.Token);
-
-        byte[] response = new byte[12];
-        await ReadExactlyAsync(stream, response, timeoutCts.Token);
-
-        if (response[0] != request[0] || response[1] != request[1])
+        await _transportLock.WaitAsync(cancellationToken);
+        try
         {
-            throw new InvalidOperationException("PLC 响应事务号不匹配。");
+            using var client = new TcpClient();
+            using var timeoutCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+            timeoutCts.CancelAfter(TimeSpan.FromMilliseconds(config.TimeoutMilliseconds));
+
+            await client.ConnectAsync(config.IpAddress, config.Port, timeoutCts.Token);
+            await using NetworkStream stream = client.GetStream();
+
+            ushort transactionId = NextTransactionId();
+            byte[] request = BuildWriteSingleCoilRequest(transactionId, config.UnitId, coilAddress, value);
+            await stream.WriteAsync(request, timeoutCts.Token);
+
+            byte[] response = new byte[12];
+            await ReadExactlyAsync(stream, response, timeoutCts.Token);
+            ValidateFixedResponseHeader(response, request);
+
+            if (response[7] == 0x85)
+            {
+                throw new InvalidOperationException($"PLC 写线圈异常，功能码 0x05，异常码 0x{response[8]:X2}。");
+            }
+
+            if (response[7] != 0x05)
+            {
+                throw new InvalidOperationException($"PLC 响应功能码无效：0x{response[7]:X2}。");
+            }
+
+            if (!response.AsSpan(8, 4).SequenceEqual(request.AsSpan(8, 4)))
+            {
+                throw new InvalidOperationException("PLC 写线圈响应地址或值不匹配。");
+            }
         }
-
-        if (response[7] == 0x85)
+        finally
         {
-            throw new InvalidOperationException($"PLC 写线圈异常，功能码 0x05，异常码 0x{response[8]:X2}。");
-        }
-
-        if (response[7] != 0x05)
-        {
-            throw new InvalidOperationException($"PLC 响应功能码无效：0x{response[7]:X2}。");
+            _transportLock.Release();
         }
     }
 
     private async Task<ushort[]> ReadHoldingRegistersAsync(PlcConnectionConfig config, ushort startAddress, ushort numberOfPoints, CancellationToken cancellationToken)
     {
-        using var client = new TcpClient();
-        using var timeoutCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
-        timeoutCts.CancelAfter(TimeSpan.FromMilliseconds(config.TimeoutMilliseconds));
-
-        await client.ConnectAsync(config.IpAddress, config.Port, timeoutCts.Token);
-        await using NetworkStream stream = client.GetStream();
-
-        ushort transactionId = NextTransactionId();
-        byte[] request = BuildReadHoldingRegistersRequest(transactionId, config.UnitId, startAddress, numberOfPoints);
-        await stream.WriteAsync(request, timeoutCts.Token);
-
-        byte[] header = new byte[7];
-        await ReadExactlyAsync(stream, header, timeoutCts.Token);
-        int remainingLength = BinaryPrimitives.ReadUInt16BigEndian(header.AsSpan(4, 2)) - 1;
-        if (remainingLength <= 0)
+        await _transportLock.WaitAsync(cancellationToken);
+        try
         {
-            throw new InvalidOperationException("PLC 响应长度无效。");
+            using var client = new TcpClient();
+            using var timeoutCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+            timeoutCts.CancelAfter(TimeSpan.FromMilliseconds(config.TimeoutMilliseconds));
+
+            await client.ConnectAsync(config.IpAddress, config.Port, timeoutCts.Token);
+            await using NetworkStream stream = client.GetStream();
+
+            ushort transactionId = NextTransactionId();
+            byte[] request = BuildReadHoldingRegistersRequest(transactionId, config.UnitId, startAddress, numberOfPoints);
+            await stream.WriteAsync(request, timeoutCts.Token);
+
+            byte[] header = new byte[7];
+            await ReadExactlyAsync(stream, header, timeoutCts.Token);
+            int remainingLength = ValidateReadResponseHeader(header, request);
+
+            byte[] pdu = new byte[remainingLength];
+            await ReadExactlyAsync(stream, pdu, timeoutCts.Token);
+
+            if (pdu[0] == 0x83)
+            {
+                byte exceptionCode = pdu.Length > 1 ? pdu[1] : (byte)0;
+                throw new InvalidOperationException($"PLC 读寄存器异常，功能码 0x03，异常码 0x{exceptionCode:X2}。");
+            }
+
+            if (pdu[0] != 0x03)
+            {
+                throw new InvalidOperationException($"PLC 响应功能码无效：0x{pdu[0]:X2}。");
+            }
+
+            int byteCount = pdu[1];
+            if (byteCount != numberOfPoints * 2 || pdu.Length < 2 + byteCount)
+            {
+                throw new InvalidOperationException("PLC 读寄存器响应字节数无效。");
+            }
+
+            ushort[] registers = new ushort[numberOfPoints];
+            for (int i = 0; i < registers.Length; i++)
+            {
+                registers[i] = BinaryPrimitives.ReadUInt16BigEndian(pdu.AsSpan(2 + i * 2, 2));
+            }
+
+            return registers;
         }
-
-        byte[] pdu = new byte[remainingLength];
-        await ReadExactlyAsync(stream, pdu, timeoutCts.Token);
-
-        if (header[0] != request[0] || header[1] != request[1])
+        finally
         {
-            throw new InvalidOperationException("PLC 响应事务号不匹配。");
+            _transportLock.Release();
         }
-
-        if (pdu[0] == 0x83)
-        {
-            byte exceptionCode = pdu.Length > 1 ? pdu[1] : (byte)0;
-            throw new InvalidOperationException($"PLC 读寄存器异常，功能码 0x03，异常码 0x{exceptionCode:X2}。");
-        }
-
-        if (pdu[0] != 0x03)
-        {
-            throw new InvalidOperationException($"PLC 响应功能码无效：0x{pdu[0]:X2}。");
-        }
-
-        int byteCount = pdu[1];
-        if (byteCount != numberOfPoints * 2 || pdu.Length < 2 + byteCount)
-        {
-            throw new InvalidOperationException("PLC 读寄存器响应字节数无效。");
-        }
-
-        ushort[] registers = new ushort[numberOfPoints];
-        for (int i = 0; i < registers.Length; i++)
-        {
-            registers[i] = BinaryPrimitives.ReadUInt16BigEndian(pdu.AsSpan(2 + i * 2, 2));
-        }
-
-        return registers;
     }
 
     private async Task<bool[]> ReadCoilsAsync(PlcConnectionConfig config, ushort startAddress, ushort numberOfPoints, CancellationToken cancellationToken)
     {
-        using var client = new TcpClient();
-        using var timeoutCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
-        timeoutCts.CancelAfter(TimeSpan.FromMilliseconds(config.TimeoutMilliseconds));
+        await _transportLock.WaitAsync(cancellationToken);
+        try
+        {
+            using var client = new TcpClient();
+            using var timeoutCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+            timeoutCts.CancelAfter(TimeSpan.FromMilliseconds(config.TimeoutMilliseconds));
 
-        await client.ConnectAsync(config.IpAddress, config.Port, timeoutCts.Token);
-        await using NetworkStream stream = client.GetStream();
+            await client.ConnectAsync(config.IpAddress, config.Port, timeoutCts.Token);
+            await using NetworkStream stream = client.GetStream();
 
-        ushort transactionId = NextTransactionId();
-        byte[] request = BuildReadCoilsRequest(transactionId, config.UnitId, startAddress, numberOfPoints);
-        await stream.WriteAsync(request, timeoutCts.Token);
+            ushort transactionId = NextTransactionId();
+            byte[] request = BuildReadCoilsRequest(transactionId, config.UnitId, startAddress, numberOfPoints);
+            await stream.WriteAsync(request, timeoutCts.Token);
 
-        byte[] header = new byte[7];
-        await ReadExactlyAsync(stream, header, timeoutCts.Token);
+            byte[] header = new byte[7];
+            await ReadExactlyAsync(stream, header, timeoutCts.Token);
+            int remainingLength = ValidateReadResponseHeader(header, request);
+
+            byte[] pdu = new byte[remainingLength];
+            await ReadExactlyAsync(stream, pdu, timeoutCts.Token);
+
+            if (pdu[0] == 0x81)
+            {
+                byte exceptionCode = pdu.Length > 1 ? pdu[1] : (byte)0;
+                throw new InvalidOperationException($"PLC 读线圈异常，功能码 0x01，异常码 0x{exceptionCode:X2}。");
+            }
+
+            if (pdu[0] != 0x01)
+            {
+                throw new InvalidOperationException($"PLC 响应功能码无效：0x{pdu[0]:X2}。");
+            }
+
+            int expectedByteCount = (numberOfPoints + 7) / 8;
+            int byteCount = pdu[1];
+            if (byteCount != expectedByteCount || pdu.Length < 2 + byteCount)
+            {
+                throw new InvalidOperationException("PLC 读线圈响应字节数无效。");
+            }
+
+            bool[] coils = new bool[numberOfPoints];
+            for (int i = 0; i < coils.Length; i++)
+            {
+                coils[i] = (pdu[2 + i / 8] & (1 << (i % 8))) != 0;
+            }
+
+            return coils;
+        }
+        finally
+        {
+            _transportLock.Release();
+        }
+    }
+
+    private async Task WriteMultipleRegistersAsync(PlcConnectionConfig config, ushort startAddress, ushort[] values, CancellationToken cancellationToken)
+    {
+        await _transportLock.WaitAsync(cancellationToken);
+        try
+        {
+            using var client = new TcpClient();
+            using var timeoutCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+            timeoutCts.CancelAfter(TimeSpan.FromMilliseconds(config.TimeoutMilliseconds));
+
+            await client.ConnectAsync(config.IpAddress, config.Port, timeoutCts.Token);
+            await using NetworkStream stream = client.GetStream();
+
+            ushort transactionId = NextTransactionId();
+            byte[] request = BuildWriteMultipleRegistersRequest(transactionId, config.UnitId, startAddress, values);
+            await stream.WriteAsync(request, timeoutCts.Token);
+
+            byte[] response = new byte[12];
+            await ReadExactlyAsync(stream, response, timeoutCts.Token);
+            ValidateFixedResponseHeader(response, request);
+
+            if (response[7] == 0x90)
+            {
+                throw new InvalidOperationException($"PLC 写寄存器异常，功能码 0x10，异常码 0x{response[8]:X2}。");
+            }
+
+            if (response[7] != 0x10)
+            {
+                throw new InvalidOperationException($"PLC 响应功能码无效：0x{response[7]:X2}。");
+            }
+
+            ushort responseStart = BinaryPrimitives.ReadUInt16BigEndian(response.AsSpan(8, 2));
+            ushort responseCount = BinaryPrimitives.ReadUInt16BigEndian(response.AsSpan(10, 2));
+            if (responseStart != startAddress || responseCount != values.Length)
+            {
+                throw new InvalidOperationException("PLC 写寄存器响应地址或数量不匹配。");
+            }
+        }
+        finally
+        {
+            _transportLock.Release();
+        }
+    }
+
+    private static int ValidateReadResponseHeader(byte[] header, byte[] request)
+    {
+        ValidateMbapHeader(header, request);
         int remainingLength = BinaryPrimitives.ReadUInt16BigEndian(header.AsSpan(4, 2)) - 1;
         if (remainingLength <= 0)
         {
             throw new InvalidOperationException("PLC 响应长度无效。");
         }
 
-        byte[] pdu = new byte[remainingLength];
-        await ReadExactlyAsync(stream, pdu, timeoutCts.Token);
-
-        if (header[0] != request[0] || header[1] != request[1])
-        {
-            throw new InvalidOperationException("PLC 响应事务号不匹配。");
-        }
-
-        if (pdu[0] == 0x81)
-        {
-            byte exceptionCode = pdu.Length > 1 ? pdu[1] : (byte)0;
-            throw new InvalidOperationException($"PLC 读线圈异常，功能码 0x01，异常码 0x{exceptionCode:X2}。");
-        }
-
-        if (pdu[0] != 0x01)
-        {
-            throw new InvalidOperationException($"PLC 响应功能码无效：0x{pdu[0]:X2}。");
-        }
-
-        int expectedByteCount = (numberOfPoints + 7) / 8;
-        int byteCount = pdu[1];
-        if (byteCount != expectedByteCount || pdu.Length < 2 + byteCount)
-        {
-            throw new InvalidOperationException("PLC 读线圈响应字节数无效。");
-        }
-
-        bool[] coils = new bool[numberOfPoints];
-        for (int i = 0; i < coils.Length; i++)
-        {
-            coils[i] = (pdu[2 + i / 8] & (1 << (i % 8))) != 0;
-        }
-
-        return coils;
+        return remainingLength;
     }
 
-    private async Task WriteMultipleRegistersAsync(PlcConnectionConfig config, ushort startAddress, ushort[] values, CancellationToken cancellationToken)
+    private static void ValidateFixedResponseHeader(byte[] response, byte[] request)
     {
-        using var client = new TcpClient();
-        using var timeoutCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
-        timeoutCts.CancelAfter(TimeSpan.FromMilliseconds(config.TimeoutMilliseconds));
+        ValidateMbapHeader(response, request);
+        if (BinaryPrimitives.ReadUInt16BigEndian(response.AsSpan(4, 2)) != 6)
+        {
+            throw new InvalidOperationException("PLC 响应长度无效。");
+        }
+    }
 
-        await client.ConnectAsync(config.IpAddress, config.Port, timeoutCts.Token);
-        await using NetworkStream stream = client.GetStream();
-
-        ushort transactionId = NextTransactionId();
-        byte[] request = BuildWriteMultipleRegistersRequest(transactionId, config.UnitId, startAddress, values);
-        await stream.WriteAsync(request, timeoutCts.Token);
-
-        byte[] response = new byte[12];
-        await ReadExactlyAsync(stream, response, timeoutCts.Token);
-
-        if (response[0] != request[0] || response[1] != request[1])
+    private static void ValidateMbapHeader(ReadOnlySpan<byte> response, ReadOnlySpan<byte> request)
+    {
+        if (response.Length < 7
+            || response[0] != request[0]
+            || response[1] != request[1])
         {
             throw new InvalidOperationException("PLC 响应事务号不匹配。");
         }
 
-        if (response[7] == 0x90)
+        if (response[2] != 0 || response[3] != 0)
         {
-            throw new InvalidOperationException($"PLC 写寄存器异常，功能码 0x10，异常码 0x{response[8]:X2}。");
+            throw new InvalidOperationException("PLC 响应协议标识无效。");
         }
 
-        if (response[7] != 0x10)
+        if (response[6] != request[6])
         {
-            throw new InvalidOperationException($"PLC 响应功能码无效：0x{response[7]:X2}。");
-        }
-
-        ushort responseStart = BinaryPrimitives.ReadUInt16BigEndian(response.AsSpan(8, 2));
-        ushort responseCount = BinaryPrimitives.ReadUInt16BigEndian(response.AsSpan(10, 2));
-        if (responseStart != startAddress || responseCount != values.Length)
-        {
-            throw new InvalidOperationException("PLC 写寄存器响应地址或数量不匹配。");
+            throw new InvalidOperationException("PLC 响应站号不匹配。");
         }
     }