feat(Modbus): add WriteCoilAsync function

src/Longbow.Modbus/DefaultModbusTcpClient.cs

@@ -28,6 +28,8 @@ class DefaultModbusTcpClient(ITcpSocketClient client) : IModbusTcpClient
 
     public ValueTask<ushort[]?> ReadInputRegistersAsync(byte slaveAddress, ushort startAddress, ushort numberOfPoints) => ReadAsync(slaveAddress, 0x04, startAddress, numberOfPoints, ReadUShort);
 
+    public ValueTask<bool> WriteCoilAsync(byte slaveAddress, ushort coilAddress, bool value) => WriteBoolAsync(slaveAddress, 0x05, coilAddress, value);
+
     public ushort[] ReadWriteMultipleRegisters(byte slaveAddress, ushort startReadAddress, ushort numberOfPointsToRead, ushort startWriteAddress, ushort[] writeData)
     {
         throw new NotImplementedException();
@@ -38,11 +40,6 @@ public Task<ushort[]> ReadWriteMultipleRegistersAsync(byte slaveAddress, ushort
         throw new NotImplementedException();
     }
 
-    public void WriteFileRecord(byte slaveAdress, ushort fileNumber, ushort startingAddress, byte[] data)
-    {
-        throw new NotImplementedException();
-    }
-
     public void WriteMultipleCoils(byte slaveAddress, ushort startAddress, bool[] data)
     {
         throw new NotImplementedException();
@@ -63,16 +60,6 @@ public Task WriteMultipleRegistersAsync(byte slaveAddress, ushort startAddress,
         throw new NotImplementedException();
     }
 
-    public void WriteSingleCoil(byte slaveAddress, ushort coilAddress, bool value)
-    {
-        throw new NotImplementedException();
-    }
-
-    public Task WriteSingleCoilAsync(byte slaveAddress, ushort coilAddress, bool value)
-    {
-        throw new NotImplementedException();
-    }
-
     public void WriteSingleRegister(byte slaveAddress, ushort registerAddress, ushort value)
     {
         throw new NotImplementedException();
@@ -90,8 +77,8 @@ public Task WriteSingleRegisterAsync(byte slaveAddress, ushort registerAddress,
             throw new InvalidOperationException("站点未连接请先使用 ConnectAsync 连接设备");
         }
 
-        var data = _builder.Build(slaveAddress, functionCode, startAddress, numberOfPoints);
-        var result = await client.SendAsync(data);
+        var request = _builder.BuildReadRequest(slaveAddress, functionCode, startAddress, numberOfPoints);
+        var result = await client.SendAsync(request);
         if (!result)
         {
             return default;
@@ -101,14 +88,35 @@ public Task WriteSingleRegisterAsync(byte slaveAddress, ushort registerAddress,
         var received = await client.ReceiveAsync(_receiveCancellationTokenSource.Token);
         var response = received.Span;
 
-        if (!ValidateResponse(response, data.Span[..2], functionCode))
+        if (!ValidateResponse(response, request.Span[..2], functionCode))
         {
             return default;
         }
 
         return parser(received, numberOfPoints);
     }
 
+    private ValueTask<bool> WriteBoolAsync(byte slaveAddress, byte functionCode, ushort address, bool value)
+    {
+        if (!client.IsConnected)
+        {
+            throw new InvalidOperationException("站点未连接请先使用 ConnectAsync 连接设备");
+        }
+
+        var request = _builder.BuildWriteRequest(slaveAddress, functionCode, WriteBool(address, value));
+        return client.SendAsync(request);
+    }
+
+    private static ReadOnlyMemory<byte> WriteBool(ushort address, bool value)
+    {
+        var data = new byte[4];
+        data[0] = (byte)(address >> 8);
+        data[1] = (byte)address;
+        data[2] = value ? (byte)0xFF : (byte)0x00;
+        data[3] = 0x00;
+        return data;
+    }
+
     private static bool[] ReadBool(ReadOnlyMemory<byte> response, ushort numberOfPoints)
     {
         var values = new bool[numberOfPoints];

src/Longbow.Modbus/IModbusTcpClient.cs

@@ -69,30 +69,23 @@ public interface IModbusTcpClient : IAsyncDisposable
     /// <returns>A task that represents the asynchronous read operation.</returns>
     ValueTask<ushort[]?> ReadInputRegistersAsync(byte slaveAddress, ushort startAddress, ushort numberOfPoints);
 
-    /// <summary>
-    /// Writes a single coil value.
-    /// </summary>
-    /// <param name="slaveAddress">Address of the device to write to.</param>
-    /// <param name="coilAddress">Address to write value to.</param>
-    /// <param name="value">Value to write.</param>
-    void WriteSingleCoil(byte slaveAddress, ushort coilAddress, bool value);
-
     /// <summary>
     /// Asynchronously writes a single coil value.
     /// </summary>
     /// <param name="slaveAddress">Address of the device to write to.</param>
     /// <param name="coilAddress">Address to write value to.</param>
     /// <param name="value">Value to write.</param>
     /// <returns>A task that represents the asynchronous write operation.</returns>
-    Task WriteSingleCoilAsync(byte slaveAddress, ushort coilAddress, bool value);
+    ValueTask<bool> WriteCoilAsync(byte slaveAddress, ushort coilAddress, bool value);
 
     /// <summary>
-    /// Writes a single holding register.
+    /// Asynchronously writes a sequence of coils.
     /// </summary>
     /// <param name="slaveAddress">Address of the device to write to.</param>
-    /// <param name="registerAddress">Address to write.</param>
-    /// <param name="value">Value to write.</param>
-    void WriteSingleRegister(byte slaveAddress, ushort registerAddress, ushort value);
+    /// <param name="startAddress">Address to begin writing values.</param>
+    /// <param name="data">Values to write.</param>
+    /// <returns>A task that represents the asynchronous write operation.</returns>
+    Task WriteMultipleCoilsAsync(byte slaveAddress, ushort startAddress, bool[] data);
 
     /// <summary>
     /// Asynchronously writes a single holding register.
@@ -103,14 +96,6 @@ public interface IModbusTcpClient : IAsyncDisposable
     /// <returns>A task that represents the asynchronous write operation.</returns>
     Task WriteSingleRegisterAsync(byte slaveAddress, ushort registerAddress, ushort value);
 
-    /// <summary>
-    /// Writes a block of 1 to 123 contiguous registers.
-    /// </summary>
-    /// <param name="slaveAddress">Address of the device to write to.</param>
-    /// <param name="startAddress">Address to begin writing values.</param>
-    /// <param name="data">Values to write.</param>
-    void WriteMultipleRegisters(byte slaveAddress, ushort startAddress, ushort[] data);
-
     /// <summary>
     /// Asynchronously writes a block of 1 to 123 contiguous registers.
     /// </summary>
@@ -120,23 +105,6 @@ public interface IModbusTcpClient : IAsyncDisposable
     /// <returns>A task that represents the asynchronous write operation.</returns>
     Task WriteMultipleRegistersAsync(byte slaveAddress, ushort startAddress, ushort[] data);
 
-    /// <summary>
-    /// Writes a sequence of coils.
-    /// </summary>
-    /// <param name="slaveAddress">Address of the device to write to.</param>
-    /// <param name="startAddress">Address to begin writing values.</param>
-    /// <param name="data">Values to write.</param>
-    void WriteMultipleCoils(byte slaveAddress, ushort startAddress, bool[] data);
-
-    /// <summary>
-    /// Asynchronously writes a sequence of coils.
-    /// </summary>
-    /// <param name="slaveAddress">Address of the device to write to.</param>
-    /// <param name="startAddress">Address to begin writing values.</param>
-    /// <param name="data">Values to write.</param>
-    /// <returns>A task that represents the asynchronous write operation.</returns>
-    Task WriteMultipleCoilsAsync(byte slaveAddress, ushort startAddress, bool[] data);
-
     /// <summary>
     /// Performs a combination of one read operation and one write operation in a single Modbus transaction.
     /// The write operation is performed before the read.
@@ -169,13 +137,4 @@ Task<ushort[]> ReadWriteMultipleRegistersAsync(
             ushort numberOfPointsToRead,
             ushort startWriteAddress,
             ushort[] writeData);
-
-    /// <summary>
-    /// Write a file record to the device.
-    /// </summary>
-    /// <param name="slaveAdress">Address of device to write values to</param>
-    /// <param name="fileNumber">The Extended Memory file number</param>
-    /// <param name="startingAddress">The starting register address within the file</param>
-    /// <param name="data">The data to be written</param>
-    void WriteFileRecord(byte slaveAdress, ushort fileNumber, ushort startingAddress, byte[] data);
 }

src/Longbow.Modbus/ModbusMessageBuilder.cs

@@ -13,14 +13,14 @@ public class ModbusTcpMessageBuilder
     private ushort _transactionId = 0;
 
     /// <summary>
-    /// 构建 Modbus TCP 请求消息方法
+    /// 构建 Modbus TCP 读取消息方法
     /// </summary>
     /// <param name="slaveAddress"></param>
     /// <param name="functionCode"></param>
     /// <param name="startAddress"></param>
     /// <param name="numberOfPoints"></param>
     /// <returns></returns>
-    public ReadOnlyMemory<byte> Build(byte slaveAddress, byte functionCode, ushort startAddress, ushort numberOfPoints)
+    public ReadOnlyMemory<byte> BuildReadRequest(byte slaveAddress, byte functionCode, ushort startAddress, ushort numberOfPoints)
     {
         byte[] request =
         [
@@ -52,4 +52,44 @@ public ReadOnlyMemory<byte> Build(byte slaveAddress, byte functionCode, ushort s
 
         return request;
     }
+
+
+    /// <summary>
+    /// 构建 Modbus TCP 写入消息方法
+    /// </summary>
+    /// <param name="slaveAddress"></param>
+    /// <param name="functionCode"></param>
+    /// <param name="data"></param>
+    /// <returns></returns>
+    public ReadOnlyMemory<byte> BuildWriteRequest(byte slaveAddress, byte functionCode, ReadOnlyMemory<byte> data)
+    {
+        var request = new byte[8 + data.Length];
+
+        // MBAP头（7字节）
+        request[0] = (byte)(_transactionId >> 8);   // 00 事务标识符高字节（可随机）
+        request[1] = (byte)(_transactionId & 0xFF); // 01 事务标识符低字节
+        request[2] = 0x00;                          // 02 协议标识符高字节（Modbus固定0）
+        request[3] = 0x00;                          // 03 协议标识符低字节
+        request[4] = 0x00;                          // 04 长度高字节（后续字节数）
+        request[5] = 0x06;                          // 05 长度低字节（6字节PDU）
+
+        // PDU部分
+        request[6] = slaveAddress;                  // 06 从站地址
+        request[7] = functionCode;                  // 07 功能码
+
+        // 写入数据部分
+        data.CopyTo(request.AsMemory(8));
+
+        // 递增事务标识符以供下次使用
+        if (_transactionId == ushort.MaxValue)
+        {
+            _transactionId = 0;
+        }
+        else
+        {
+            _transactionId++;
+        }
+
+        return request;
+    }
 }

test/UnitTestModbus/TcpClientTest.cs

@@ -88,4 +88,23 @@ public async Task ReadInputRegistersAsync_Ok()
         Assert.NotNull(response);
         Assert.Equal(10, response.Length);
     }
+
+    [Fact]
+    public async Task WriteCoilAsync_Ok()
+    {
+        var sc = new ServiceCollection();
+        sc.AddTcpSocketFactory();
+        sc.AddModbusFactory();
+
+        var provider = sc.BuildServiceProvider();
+        var factory = provider.GetRequiredService<IModbusFactory>();
+        await using var client = factory.GetOrCreateTcpMaster("test");
+
+        // 连接 Master
+        await client.ConnectAsync("127.0.0.1", 502);
+
+        // 读取 0x01 从站输入寄存器数据
+        var response = await client.WriteCoilAsync(0x01, 0, true);
+        Assert.True(response);
+    }
 }