Merge branch 'dev'

CHANGELOG.md

@@ -1,3 +1,9 @@
+## v5.0.1 - 2022-11-14
+
+### Bugs Fixed
+
+- The Modbus server did not correctly detect request frames (thanks @jmsqlr, https://github.com/Apollo3zehn/FluentModbus/pull/75#issuecomment-1304653670)
+
 ## v5.0.0 - 2022-09-08
 
 ### Breaking Changes

src/FluentModbus/Client/ModbusRtuClient.cs

@@ -199,7 +199,7 @@ protected override Span<byte> TransceiveFrame(byte unitIdentifier, ModbusFunctio
                 frameLength += _serialPort!.Value.Value
                     .Read(_frameBuffer.Buffer, frameLength, _frameBuffer.Buffer.Length - frameLength);
 
-                if (ModbusUtils.DetectFrame(unitIdentifier, _frameBuffer.Buffer.AsMemory().Slice(0, frameLength)))
+                if (ModbusUtils.DetectResponseFrame(unitIdentifier, _frameBuffer.Buffer.AsMemory().Slice(0, frameLength)))
                 {
                     break;
                 }
@@ -230,6 +230,7 @@ protected override Span<byte> TransceiveFrame(byte unitIdentifier, ModbusFunctio
 
         private bool _disposedValue;
 
+        /// <inheritdoc />
         protected virtual void Dispose(bool disposing)
         {
             if (!_disposedValue)
@@ -243,6 +244,9 @@ protected virtual void Dispose(bool disposing)
             }
         }
 
+        /// <summary>
+        /// Disposes the current instance.
+        /// </summary>
         public void Dispose()
         {
             Dispose(disposing: true);

src/FluentModbus/Client/ModbusRtuClientAsync.cs

@@ -57,7 +57,7 @@ protected override async Task<Memory<byte>> TransceiveFrameAsync(byte unitIdenti
             {
                 frameLength += await _serialPort!.Value.Value.ReadAsync(_frameBuffer.Buffer, frameLength, _frameBuffer.Buffer.Length - frameLength, cancellationToken).ConfigureAwait(false);
 
-                if (ModbusUtils.DetectFrame(unitIdentifier, _frameBuffer.Buffer.AsMemory().Slice(0, frameLength)))
+                if (ModbusUtils.DetectResponseFrame(unitIdentifier, _frameBuffer.Buffer.AsMemory().Slice(0, frameLength)))
                 {
                     break;
                 }

src/FluentModbus/Client/ModbusTcpClient.cs

@@ -358,7 +358,9 @@ protected virtual void Dispose(bool disposing)
             }
         }
 
-        /// <inheritdoc />
+        /// <summary>
+        /// Diposes the current instance.
+        /// </summary>
         public void Dispose()
         {
             Dispose(disposing: true);

src/FluentModbus/FluentModbus.csproj

@@ -46,10 +46,6 @@
     </None>
   </ItemGroup>
 
-  <ItemGroup>
-    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="5.0.0" />
-  </ItemGroup>
-
   <ItemGroup>
     <Compile Update="Client\ModbusClientAsync.cs">
       <DesignTime>True</DesignTime>

src/FluentModbus/ModbusRtuSerialPort.cs

@@ -2,6 +2,9 @@
 
 namespace FluentModbus
 {
+    /// <summary>
+    /// A wrapper for a <see cref="SerialPort" />.
+    /// </summary>
     public class ModbusRtuSerialPort : IModbusRtuSerialPort
     {
         #region Fields
@@ -12,6 +15,10 @@ public class ModbusRtuSerialPort : IModbusRtuSerialPort
 
         #region Constructors
 
+        /// <summary>
+        /// Initializes a new instances of the <see cref="ModbusRtuSerialPort" /> class.
+        /// </summary>
+        /// <param name="serialPort">The serial port to wrap.</param>
         public ModbusRtuSerialPort(SerialPort serialPort)
         {
             _serialPort = serialPort;
@@ -21,8 +28,14 @@ public ModbusRtuSerialPort(SerialPort serialPort)
 
         #region Properties
 
+        /// <summary>
+        /// Gets the port for communications.
+        /// </summary>
         public string PortName => _serialPort.PortName;
 
+        /// <summary>
+        /// Gets a value indicating the open or closed status of the <see cref="ModbusRtuSerialPort" /> object.
+        /// </summary>
         public bool IsOpen => _serialPort.IsOpen;
 
         #endregion
@@ -49,8 +62,8 @@ public void Close()
         /// Reads from the <see cref="SerialPort"/> input buffer.
         /// </summary>
         /// <param name="buffer">The byte array to write the input to.</param>
-        /// <param name="offset">The offset in <see cref="buffer"/> at which to write the bytes.</param>
-        /// <param name="count">The maximum number of bytes to read. Fewer bytes are read if <see cref="count"/> is greater than the number of bytes in the input buffer.</param>
+        /// <param name="offset">The offset in <paramref name="buffer"/> at which to write the bytes.</param>
+        /// <param name="count">The maximum number of bytes to read. Fewer bytes are read if <paramref name="count"/> is greater than the number of bytes in the input buffer.</param>
         /// <returns>The number of bytes read.</returns>
         public int Read(byte[] buffer, int offset, int count)
         {
@@ -61,8 +74,8 @@ public int Read(byte[] buffer, int offset, int count)
         /// Asynchronously reads from the <see cref="SerialPort"/> input buffer.
         /// </summary>
         /// <param name="buffer">The byte array to write the input to.</param>
-        /// <param name="offset">The offset in <see cref="buffer"/> at which to write the bytes.</param>
-        /// <param name="count">The maximum number of bytes to read. Fewer bytes are read if <see cref="count"/> is greater than the number of bytes in the input buffer.</param>
+        /// <param name="offset">The offset in <paramref name="buffer"/> at which to write the bytes.</param>
+        /// <param name="count">The maximum number of bytes to read. Fewer bytes are read if <paramref name="count"/> is greater than the number of bytes in the input buffer.</param>
         /// <param name="token">A token to cancel the current operation.</param>
         /// <returns>The number of bytes read.</returns>
         public async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken token)
@@ -104,7 +117,7 @@ public async Task<int> ReadAsync(byte[] buffer, int offset, int count, Cancellat
         /// Writes data to the serial port output buffer.
         /// </summary>
         /// <param name="buffer">The byte array that contains the data to write to the port.</param>
-        /// <param name="offset">The zero-based byte offset in the <see cref="buffer"/> parameter at which to begin copying bytes to the port.</param>
+        /// <param name="offset">The zero-based byte offset in the <paramref name="buffer"/> parameter at which to begin copying bytes to the port.</param>
         /// <param name="count">The number of bytes to write.</param>
         public void Write(byte[] buffer, int offset, int count)
         {
@@ -115,7 +128,7 @@ public void Write(byte[] buffer, int offset, int count)
         /// Asynchronously writes data to the serial port output buffer.
         /// </summary>
         /// <param name="buffer">The byte array that contains the data to write to the port.</param>
-        /// <param name="offset">The zero-based byte offset in the <see cref="buffer"/> parameter at which to begin copying bytes to the port.</param>
+        /// <param name="offset">The zero-based byte offset in the <paramref name="buffer"/> parameter at which to begin copying bytes to the port.</param>
         /// <param name="count">The number of bytes to write.</param>
         /// <param name="token">A token to cancel the current operation.</param>
         public async Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken token)

src/FluentModbus/ModbusUtils.cs

@@ -74,7 +74,42 @@ public static ushort CalculateCRC(Memory<byte> buffer)
             return crc;
         }
 
-        public static bool DetectFrame(byte unitIdentifier, Memory<byte> frame)
+        public static bool DetectRequestFrame(byte unitIdentifier, Memory<byte> frame)
+        {
+#warning This method should be improved byte validating the total length against the expected length depending on the function code
+            /* Correct response frame (min. 4 bytes)
+             * 00 Unit Identifier
+             * 01 Function Code
+             * (0..x bytes - depends on function code)
+             * n-1 CRC Byte 1
+             * n   CRC Byte 2
+             */
+
+            var span = frame.Span;
+
+            if (span.Length < 4)
+                return false;
+
+            if (unitIdentifier != 255) // 255 means "skip unit identifier check"
+            {
+                var newUnitIdentifier = span[0];
+
+                if (newUnitIdentifier != unitIdentifier)
+                    return false;
+            }
+
+            // CRC check
+            var crcBytes = span.Slice(span.Length - 2, 2);
+            var actualCRC = unchecked((ushort)((crcBytes[1] << 8) + crcBytes[0]));
+            var expectedCRC = ModbusUtils.CalculateCRC(frame.Slice(0, frame.Length - 2));
+
+            if (actualCRC != expectedCRC)
+                return false;
+
+            return true;
+        }
+
+        public static bool DetectResponseFrame(byte unitIdentifier, Memory<byte> frame)
         {
             /* Correct response frame (min. 6 bytes)
              * 00 Unit Identifier

src/FluentModbus/Server/ModbusRtuRequestHandler.cs

@@ -96,7 +96,7 @@ private async Task<bool> TryReceiveRequestAsync()
                     Length += await _serialPort.ReadAsync(FrameBuffer.Buffer, Length, FrameBuffer.Buffer.Length - Length, CancellationToken);
 
                     // full frame received
-                    if (ModbusUtils.DetectFrame(255, FrameBuffer.Buffer.AsMemory(0, Length)))
+                    if (ModbusUtils.DetectRequestFrame(255, FrameBuffer.Buffer.AsMemory(0, Length)))
                     {
                         FrameBuffer.Reader.BaseStream.Seek(0, SeekOrigin.Begin);
 

version.json

@@ -1,4 +1,4 @@
 {
-    "version": "5.0.0",
+    "version": "5.0.1",
     "suffix": ""
 }