diff --git a/AMWD.Protocols.Modbus.Common/Protocols/RtuOverTcpProtocol.cs b/AMWD.Protocols.Modbus.Common/Protocols/RtuOverTcpProtocol.cs
new file mode 100644
index 0000000..00dd00b
--- /dev/null
+++ b/AMWD.Protocols.Modbus.Common/Protocols/RtuOverTcpProtocol.cs
@@ -0,0 +1,764 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using AMWD.Protocols.Modbus.Common.Contracts;
+
+namespace AMWD.Protocols.Modbus.Common.Protocols
+{
+ ///
+ /// Implementation of the Modbus RTU over TCP protocol.
+ ///
+ ///
+ /// The Modbus RTU over Modbus TCP is rarely used.
+ /// It is a non-standard variant of Modbus TCP that includes the Modbus RTU CRC at the end of the message.
+ ///
+ public class RtuOverTcpProtocol : IModbusProtocol
+ {
+ #region Fields
+
+ private readonly object _lock = new();
+ private ushort _transactionId = 0x0000;
+
+ #endregion Fields
+
+ #region Constants
+
+ ///
+ /// The minimum allowed unit id specified by the Modbus SerialLine protocol.
+ ///
+ ///
+ /// INFORMATION:
+ ///
+ /// Reading the specification, the minimum allowed unit ID would be 1.
+ ///
+ /// As of other implementations seen, this limit is not enforced!
+ ///
+ public const byte MIN_UNIT_ID = 0x01;
+
+ ///
+ /// The maximum allowed unit id specified by the Modbus SerialLine protocol.
+ ///
+ ///
+ /// Reading the specification, the max allowed unit id would be 247!
+ ///
+ public const byte MAX_UNIT_ID = 0xFF;
+
+ ///
+ /// The minimum allowed read count specified by the Modbus SerialLine protocol.
+ ///
+ public const ushort MIN_READ_COUNT = 0x01;
+
+ ///
+ /// The minimum allowed write count specified by the Modbus SerialLine protocol.
+ ///
+ public const ushort MIN_WRITE_COUNT = 0x01;
+
+ ///
+ /// The maximum allowed read count for discrete values specified by the Modbus SerialLine protocol.
+ ///
+ public const ushort MAX_DISCRETE_READ_COUNT = 0x07D0; // 2000
+
+ ///
+ /// The maximum allowed write count for discrete values specified by the Modbus SerialLine protocol.
+ ///
+ public const ushort MAX_DISCRETE_WRITE_COUNT = 0x07B0; // 1968
+
+ ///
+ /// The maximum allowed read count for registers specified by the Modbus SerialLine protocol.
+ ///
+ public const ushort MAX_REGISTER_READ_COUNT = 0x007D; // 125
+
+ ///
+ /// The maximum allowed write count for registers specified by the Modbus SerialLine protocol.
+ ///
+ public const ushort MAX_REGISTER_WRITE_COUNT = 0x007B; // 123
+
+ ///
+ /// The maximum allowed ADU length in bytes.
+ ///
+ ///
+ /// A Modbus frame consists of a PDU (protcol data unit) and additional protocol addressing / error checks.
+ /// The whole data frame is called ADU (application data unit).
+ ///
+ public const int MAX_ADU_LENGTH = 262; // bytes
+
+ #endregion Constants
+
+ ///
+ public string Name => "RTU over TCP";
+
+ ///
+ /// Gets or sets a value indicating whether to disable the transaction id usage.
+ ///
+ public bool DisableTransactionId { get; set; }
+
+ #region Read
+
+ ///
+ public IReadOnlyList SerializeReadCoils(byte unitId, ushort startAddress, ushort count)
+ {
+ if (count < MIN_READ_COUNT || MAX_DISCRETE_READ_COUNT < count)
+ throw new ArgumentOutOfRangeException(nameof(count));
+
+ if (ushort.MaxValue < (startAddress + count - 1))
+ throw new ArgumentOutOfRangeException(nameof(count), $"Combination of {nameof(startAddress)} and {nameof(count)} exceeds the addressation limit of {ushort.MaxValue}");
+
+ byte[] request = new byte[14];
+
+ byte[] header = GetHeader(8);
+ Array.Copy(header, 0, request, 0, header.Length);
+
+ // Unit Id
+ request[6] = unitId;
+
+ // Function code
+ request[7] = (byte)ModbusFunctionCode.ReadCoils;
+
+ // Starting address
+ byte[] addrBytes = startAddress.ToBigEndianBytes();
+ request[8] = addrBytes[0];
+ request[9] = addrBytes[1];
+
+ // Quantity
+ byte[] countBytes = count.ToBigEndianBytes();
+ request[10] = countBytes[0];
+ request[11] = countBytes[1];
+
+ // CRC
+ byte[] crc = RtuProtocol.CRC16(request, 6, 6);
+ request[12] = crc[0];
+ request[13] = crc[1];
+
+ return request;
+ }
+
+ ///
+ public IReadOnlyList DeserializeReadCoils(IReadOnlyList response)
+ {
+ int baseOffset = 9;
+ if (response[8] != response.Count - baseOffset - 2) // -2 for CRC
+ throw new ModbusException("Coil byte count does not match.");
+
+ int count = response[8] * 8;
+ var coils = new List();
+ for (int i = 0; i < count; i++)
+ {
+ int bytePosition = i / 8;
+ int bitPosition = i % 8;
+
+ int value = response[baseOffset + bytePosition] & (1 << bitPosition);
+ coils.Add(new Coil
+ {
+ Address = (ushort)i,
+ Value = value > 0
+ });
+ }
+
+ return coils;
+ }
+
+ ///
+ public IReadOnlyList SerializeReadDiscreteInputs(byte unitId, ushort startAddress, ushort count)
+ {
+ if (count < MIN_READ_COUNT || MAX_DISCRETE_READ_COUNT < count)
+ throw new ArgumentOutOfRangeException(nameof(count));
+
+ if (ushort.MaxValue < (startAddress + count - 1))
+ throw new ArgumentOutOfRangeException(nameof(count), $"Combination of {nameof(startAddress)} and {nameof(count)} exceeds the addressation limit of {ushort.MaxValue}");
+
+ byte[] request = new byte[14];
+
+ byte[] header = GetHeader(8);
+ Array.Copy(header, 0, request, 0, header.Length);
+
+ // Unit Id
+ request[6] = unitId;
+
+ // Function code
+ request[7] = (byte)ModbusFunctionCode.ReadDiscreteInputs;
+
+ // Starting address
+ byte[] addrBytes = startAddress.ToBigEndianBytes();
+ request[8] = addrBytes[0];
+ request[9] = addrBytes[1];
+
+ // Quantity
+ byte[] countBytes = count.ToBigEndianBytes();
+ request[10] = countBytes[0];
+ request[11] = countBytes[1];
+
+ // CRC
+ byte[] crc = RtuProtocol.CRC16(request, 6, 6);
+ request[12] = crc[0];
+ request[13] = crc[1];
+
+ return request;
+ }
+
+ ///
+ public IReadOnlyList DeserializeReadDiscreteInputs(IReadOnlyList response)
+ {
+ int baseOffset = 9;
+ if (response[8] != response.Count - baseOffset - 2) // -2 for CRC
+ throw new ModbusException("Discrete input byte count does not match.");
+
+ int count = response[8] * 8;
+ var discreteInputs = new List();
+ for (int i = 0; i < count; i++)
+ {
+ int bytePosition = i / 8;
+ int bitPosition = i % 8;
+
+ int value = response[baseOffset + bytePosition] & (1 << bitPosition);
+ discreteInputs.Add(new DiscreteInput
+ {
+ Address = (ushort)i,
+ HighByte = (byte)(value > 0 ? 0xFF : 0x00)
+ });
+ }
+
+ return discreteInputs;
+ }
+
+ ///
+ public IReadOnlyList SerializeReadHoldingRegisters(byte unitId, ushort startAddress, ushort count)
+ {
+ if (count < MIN_READ_COUNT || MAX_REGISTER_READ_COUNT < count)
+ throw new ArgumentOutOfRangeException(nameof(count));
+
+ if (ushort.MaxValue < (startAddress + count - 1))
+ throw new ArgumentOutOfRangeException(nameof(count), $"Combination of {nameof(startAddress)} and {nameof(count)} exceeds the addressation limit of {ushort.MaxValue}");
+
+ byte[] request = new byte[14];
+
+ byte[] header = GetHeader(8);
+ Array.Copy(header, 0, request, 0, header.Length);
+
+ // Unit Id
+ request[6] = unitId;
+
+ // Function code
+ request[7] = (byte)ModbusFunctionCode.ReadHoldingRegisters;
+
+ // Starting address
+ byte[] addrBytes = startAddress.ToBigEndianBytes();
+ request[8] = addrBytes[0];
+ request[9] = addrBytes[1];
+
+ // Quantity
+ byte[] countBytes = count.ToBigEndianBytes();
+ request[10] = countBytes[0];
+ request[11] = countBytes[1];
+
+ // CRC
+ byte[] crc = RtuProtocol.CRC16(request, 6, 6);
+ request[12] = crc[0];
+ request[13] = crc[1];
+
+ return request;
+ }
+
+ ///
+ public IReadOnlyList DeserializeReadHoldingRegisters(IReadOnlyList response)
+ {
+ int baseOffset = 9;
+ if (response[8] != response.Count - baseOffset - 2)
+ throw new ModbusException("Holding register byte count does not match.");
+
+ int count = response[8] / 2;
+ var holdingRegisters = new List();
+ for (int i = 0; i < count; i++)
+ {
+ holdingRegisters.Add(new HoldingRegister
+ {
+ Address = (ushort)i,
+ HighByte = response[baseOffset + i * 2],
+ LowByte = response[baseOffset + i * 2 + 1]
+ });
+ }
+
+ return holdingRegisters;
+ }
+
+ ///
+ public IReadOnlyList SerializeReadInputRegisters(byte unitId, ushort startAddress, ushort count)
+ {
+ if (count < MIN_READ_COUNT || MAX_REGISTER_READ_COUNT < count)
+ throw new ArgumentOutOfRangeException(nameof(count));
+
+ if (ushort.MaxValue < (startAddress + count - 1))
+ throw new ArgumentOutOfRangeException(nameof(count), $"Combination of {nameof(startAddress)} and {nameof(count)} exceeds the addressation limit of {ushort.MaxValue}");
+
+ byte[] request = new byte[14];
+
+ byte[] header = GetHeader(8);
+ Array.Copy(header, 0, request, 0, header.Length);
+
+ // Unit Id
+ request[6] = unitId;
+
+ // Function code
+ request[7] = (byte)ModbusFunctionCode.ReadInputRegisters;
+
+ // Starting address
+ byte[] addrBytes = startAddress.ToBigEndianBytes();
+ request[8] = addrBytes[0];
+ request[9] = addrBytes[1];
+
+ // Quantity
+ byte[] countBytes = count.ToBigEndianBytes();
+ request[10] = countBytes[0];
+ request[11] = countBytes[1];
+
+ // CRC
+ byte[] crc = RtuProtocol.CRC16(request, 6, 6);
+ request[12] = crc[0];
+ request[13] = crc[1];
+
+ return request;
+ }
+
+ ///
+ public IReadOnlyList DeserializeReadInputRegisters(IReadOnlyList response)
+ {
+ int baseOffset = 9;
+ if (response[8] != response.Count - baseOffset - 2)
+ throw new ModbusException("Input register byte count does not match.");
+
+ int count = response[8] / 2;
+ var inputRegisters = new List();
+ for (int i = 0; i < count; i++)
+ {
+ inputRegisters.Add(new InputRegister
+ {
+ Address = (ushort)i,
+ HighByte = response[baseOffset + i * 2],
+ LowByte = response[baseOffset + i * 2 + 1]
+ });
+ }
+
+ return inputRegisters;
+ }
+
+ ///
+ public IReadOnlyList SerializeReadDeviceIdentification(byte unitId, ModbusDeviceIdentificationCategory category, ModbusDeviceIdentificationObject objectId)
+ {
+ if (!Enum.IsDefined(typeof(ModbusDeviceIdentificationCategory), category))
+ throw new ArgumentOutOfRangeException(nameof(category));
+
+ byte[] request = new byte[13];
+
+ byte[] header = GetHeader(7);
+ Array.Copy(header, 0, request, 0, header.Length);
+
+ // Unit Id
+ request[6] = unitId;
+
+ // Function code
+ request[7] = (byte)ModbusFunctionCode.EncapsulatedInterface;
+
+ // Modbus Encapsulated Interface: Read Device Identification (MEI Type)
+ request[8] = 0x0E;
+
+ // The category type (basic, regular, extended, individual)
+ request[9] = (byte)category;
+ request[10] = (byte)objectId;
+
+ // CRC
+ byte[] crc = RtuProtocol.CRC16(request, 6, 5);
+ request[11] = crc[0];
+ request[12] = crc[1];
+
+ return request;
+ }
+
+ ///
+ public DeviceIdentificationRaw DeserializeReadDeviceIdentification(IReadOnlyList response)
+ {
+ if (response[8] != 0x0E)
+ throw new ModbusException("The MEI type does not match");
+
+ if (!Enum.IsDefined(typeof(ModbusDeviceIdentificationCategory), response[9]))
+ throw new ModbusException("The category type does not match");
+
+ var deviceIdentification = new DeviceIdentificationRaw
+ {
+ AllowsIndividualAccess = (response[10] & 0x80) == 0x80,
+ MoreRequestsNeeded = response[11] == 0xFF,
+ NextObjectIdToRequest = response[12],
+ };
+
+ int baseOffset = 14;
+ while (baseOffset < response.Count - 2) // -2 for CRC
+ {
+ byte objectId = response[baseOffset];
+ byte length = response[baseOffset + 1];
+
+ byte[] data = response.Skip(baseOffset + 2).Take(length).ToArray();
+
+ deviceIdentification.Objects.Add(objectId, data);
+ baseOffset += 2 + length;
+ }
+
+ return deviceIdentification;
+ }
+
+ #endregion Read
+
+ #region Write
+
+ ///
+ public IReadOnlyList SerializeWriteSingleCoil(byte unitId, Coil coil)
+ {
+#if NET8_0_OR_GREATER
+ ArgumentNullException.ThrowIfNull(coil);
+#else
+ if (coil == null)
+ throw new ArgumentNullException(nameof(coil));
+#endif
+
+ byte[] request = new byte[14];
+
+ byte[] header = GetHeader(8);
+ Array.Copy(header, 0, request, 0, header.Length);
+
+ // Unit ID
+ request[6] = unitId;
+
+ // Function code
+ request[7] = (byte)ModbusFunctionCode.WriteSingleCoil;
+
+ byte[] addrBytes = coil.Address.ToBigEndianBytes();
+ request[8] = addrBytes[0];
+ request[9] = addrBytes[1];
+
+ request[10] = coil.HighByte;
+ request[11] = coil.LowByte;
+
+ // CRC
+ byte[] crc = RtuProtocol.CRC16(request, 6, 6);
+ request[12] = crc[0];
+ request[13] = crc[1];
+
+ return request;
+ }
+
+ ///
+ public Coil DeserializeWriteSingleCoil(IReadOnlyList response)
+ {
+ return new Coil
+ {
+ Address = response.ToArray().GetBigEndianUInt16(8),
+ HighByte = response[10],
+ LowByte = response[11]
+ };
+ }
+
+ ///
+ public IReadOnlyList SerializeWriteSingleHoldingRegister(byte unitId, HoldingRegister register)
+ {
+#if NET8_0_OR_GREATER
+ ArgumentNullException.ThrowIfNull(register);
+#else
+ if (register == null)
+ throw new ArgumentNullException(nameof(register));
+#endif
+
+ byte[] request = new byte[14];
+
+ byte[] header = GetHeader(8);
+ Array.Copy(header, 0, request, 0, header.Length);
+
+ // Unit Id
+ request[6] = unitId;
+
+ // Function code
+ request[7] = (byte)ModbusFunctionCode.WriteSingleRegister;
+
+ byte[] addrBytes = register.Address.ToBigEndianBytes();
+ request[8] = addrBytes[0];
+ request[9] = addrBytes[1];
+
+ request[10] = register.HighByte;
+ request[11] = register.LowByte;
+
+ // CRC
+ byte[] crc = RtuProtocol.CRC16(request, 6, 6);
+ request[12] = crc[0];
+ request[13] = crc[1];
+
+ return request;
+ }
+
+ ///
+ public HoldingRegister DeserializeWriteSingleHoldingRegister(IReadOnlyList response)
+ {
+ return new HoldingRegister
+ {
+ Address = response.ToArray().GetBigEndianUInt16(8),
+ HighByte = response[10],
+ LowByte = response[11]
+ };
+ }
+
+ ///
+ public IReadOnlyList SerializeWriteMultipleCoils(byte unitId, IReadOnlyList coils)
+ {
+#if NET8_0_OR_GREATER
+ ArgumentNullException.ThrowIfNull(coils);
+#else
+ if (coils == null)
+ throw new ArgumentNullException(nameof(coils));
+#endif
+
+ var orderedList = coils.OrderBy(c => c.Address).ToList();
+ if (orderedList.Count < MIN_WRITE_COUNT || MAX_DISCRETE_WRITE_COUNT < orderedList.Count)
+ throw new ArgumentOutOfRangeException(nameof(coils), $"At least {MIN_WRITE_COUNT} or max. {MAX_DISCRETE_WRITE_COUNT} coils can be written at once.");
+
+ int addrCount = coils.Select(c => c.Address).Distinct().Count();
+ if (orderedList.Count != addrCount)
+ throw new ArgumentException("One or more duplicate coils found.", nameof(coils));
+
+ ushort firstAddress = orderedList.First().Address;
+ ushort lastAddress = orderedList.Last().Address;
+
+ if (firstAddress + orderedList.Count - 1 != lastAddress)
+ throw new ArgumentException("Gap in coil list found.", nameof(coils));
+
+ byte byteCount = (byte)Math.Ceiling(orderedList.Count / 8.0);
+ byte[] request = new byte[15 + byteCount];
+
+ byte[] header = GetHeader(byteCount + 9);
+ Array.Copy(header, 0, request, 0, header.Length);
+
+ // Unit id
+ request[6] = unitId;
+
+ // Function code
+ request[7] = (byte)ModbusFunctionCode.WriteMultipleCoils;
+
+ // Starting address
+ byte[] addrBytes = firstAddress.ToBigEndianBytes();
+ request[8] = addrBytes[0];
+ request[9] = addrBytes[1];
+
+ // Quantity
+ byte[] countBytes = ((ushort)orderedList.Count).ToBigEndianBytes();
+ request[10] = countBytes[0];
+ request[11] = countBytes[1];
+
+ // Byte count
+ request[12] = byteCount;
+
+ // Coils
+ int baseOffset = 13;
+ for (int i = 0; i < orderedList.Count; i++)
+ {
+ int bytePosition = i / 8;
+ int bitPosition = i % 8;
+
+ if (orderedList[i].Value)
+ {
+ byte bitMask = (byte)(1 << bitPosition);
+ request[baseOffset + bytePosition] |= bitMask;
+ }
+ }
+
+ // CRC
+ byte[] crc = RtuProtocol.CRC16(request, 6, request.Length - 8);
+ request[request.Length - 2] = crc[0];
+ request[request.Length - 1] = crc[1];
+
+ return request;
+ }
+
+ ///
+ public (ushort FirstAddress, ushort NumberOfCoils) DeserializeWriteMultipleCoils(IReadOnlyList response)
+ {
+ ushort firstAddress = response.ToArray().GetBigEndianUInt16(8);
+ ushort numberOfCoils = response.ToArray().GetBigEndianUInt16(10);
+
+ return (firstAddress, numberOfCoils);
+ }
+
+ ///
+ public IReadOnlyList SerializeWriteMultipleHoldingRegisters(byte unitId, IReadOnlyList registers)
+ {
+#if NET8_0_OR_GREATER
+ ArgumentNullException.ThrowIfNull(registers);
+#else
+ if (registers == null)
+ throw new ArgumentNullException(nameof(registers));
+#endif
+
+ var orderedList = registers.OrderBy(c => c.Address).ToList();
+ if (orderedList.Count < MIN_WRITE_COUNT || MAX_REGISTER_WRITE_COUNT < orderedList.Count)
+ throw new ArgumentOutOfRangeException(nameof(registers), $"At least {MIN_WRITE_COUNT} or max. {MAX_REGISTER_WRITE_COUNT} holding registers can be written at once.");
+
+ int addrCount = registers.Select(c => c.Address).Distinct().Count();
+ if (orderedList.Count != addrCount)
+ throw new ArgumentException("One or more duplicate holding registers found.", nameof(registers));
+
+ ushort firstAddress = orderedList.First().Address;
+ ushort lastAddress = orderedList.Last().Address;
+
+ if (firstAddress + orderedList.Count - 1 != lastAddress)
+ throw new ArgumentException("Gap in holding register list found.", nameof(registers));
+
+ byte byteCount = (byte)(orderedList.Count * 2);
+ byte[] request = new byte[15 + byteCount];
+
+ byte[] header = GetHeader(byteCount + 9);
+ Array.Copy(header, 0, request, 0, header.Length);
+
+ // Unit id
+ request[6] = unitId;
+
+ // Function code
+ request[7] = (byte)ModbusFunctionCode.WriteMultipleRegisters;
+
+ // Starting address
+ byte[] addrBytes = firstAddress.ToBigEndianBytes();
+ request[8] = addrBytes[0];
+ request[9] = addrBytes[1];
+
+ // Quantity
+ byte[] countBytes = ((ushort)orderedList.Count).ToBigEndianBytes();
+ request[10] = countBytes[0];
+ request[11] = countBytes[1];
+
+ // Byte count
+ request[12] = byteCount;
+
+ // Registers
+ int baseOffset = 13;
+ for (int i = 0; i < orderedList.Count; i++)
+ {
+ request[baseOffset + 2 * i] = orderedList[i].HighByte;
+ request[baseOffset + 2 * i + 1] = orderedList[i].LowByte;
+ }
+
+ // CRC
+ byte[] crc = RtuProtocol.CRC16(request, 6, request.Length - 8);
+ request[request.Length - 2] = crc[0];
+ request[request.Length - 1] = crc[1];
+
+ return request;
+ }
+
+ ///
+ public (ushort FirstAddress, ushort NumberOfRegisters) DeserializeWriteMultipleHoldingRegisters(IReadOnlyList response)
+ {
+ ushort firstAddress = response.ToArray().GetBigEndianUInt16(8);
+ ushort numberOfRegisters = response.ToArray().GetBigEndianUInt16(10);
+
+ return (firstAddress, numberOfRegisters);
+ }
+
+ #endregion Write
+
+ #region Validation
+
+ ///
+ public bool CheckResponseComplete(IReadOnlyList responseBytes)
+ {
+ // 2x Transaction Id
+ // 2x Protocol Identifier
+ // 2x Number of following bytes
+ if (responseBytes.Count < 6)
+ return false;
+
+ ushort followingBytes = responseBytes.ToArray().GetBigEndianUInt16(4);
+ if (responseBytes.Count < followingBytes + 6)
+ return false;
+
+ return true;
+ }
+
+ ///
+ public void ValidateResponse(IReadOnlyList request, IReadOnlyList response)
+ {
+ if (!DisableTransactionId)
+ {
+ if (request[0] != response[0] || request[1] != response[1])
+ throw new ModbusException("Transaction Id does not match.");
+ }
+
+ if (request[2] != response[2] || request[3] != response[3])
+ throw new ModbusException("Protocol Identifier does not match.");
+
+ ushort count = response.ToArray().GetBigEndianUInt16(4);
+ if (count != response.Count - 6)
+ throw new ModbusException("Number of following bytes does not match.");
+
+ byte[] calculatedCrc16 = RtuProtocol.CRC16(response, 6, response.Count - 8);
+ byte[] receivedCrc16 = [response[response.Count - 2], response[response.Count - 1]];
+
+ if (calculatedCrc16[0] != receivedCrc16[0] || calculatedCrc16[1] != receivedCrc16[1])
+ throw new ModbusException("CRC16 check failed.");
+
+ if (request[6] != response[6])
+ throw new ModbusException("Unit Identifier does not match.");
+
+ byte fnCode = response[7];
+ bool isError = (fnCode & 0x80) == 0x80;
+ if (isError)
+ fnCode = (byte)(fnCode ^ 0x80); // === fnCode & 0x7F
+
+ if (request[7] != fnCode)
+ throw new ModbusException("Function code does not match.");
+
+ if (isError)
+ throw new ModbusException("Remote Error") { ErrorCode = (ModbusErrorCode)response[8] };
+ }
+
+ #endregion Validation
+
+ #region Private Helpers
+
+ private ushort GetNextTransacitonId()
+ {
+ if (DisableTransactionId)
+ return 0x0000;
+
+ lock (_lock)
+ {
+ if (_transactionId == ushort.MaxValue)
+ _transactionId = 0x0000;
+ else
+ _transactionId++;
+
+ return _transactionId;
+ }
+ }
+
+ ///
+ /// Generates the header for a Modbus request.
+ ///
+ /// The number of following bytes.
+ /// The header ready to copy to the request bytes (6 bytes).
+ private byte[] GetHeader(int followingBytes)
+ {
+ byte[] header = new byte[6];
+
+ // Transaction id
+ ushort txId = GetNextTransacitonId();
+ byte[] txBytes = txId.ToBigEndianBytes();
+ header[0] = txBytes[0];
+ header[1] = txBytes[1];
+
+ // Protocol identifier
+ header[2] = 0x00;
+ header[3] = 0x00;
+
+ // Number of following bytes
+ byte[] countBytes = ((ushort)followingBytes).ToBigEndianBytes();
+ header[4] = countBytes[0];
+ header[5] = countBytes[1];
+
+ return header;
+ }
+
+ #endregion Private Helpers
+ }
+}
diff --git a/AMWD.Protocols.Modbus.Common/README.md b/AMWD.Protocols.Modbus.Common/README.md
index 35c7aff..1f7679f 100644
--- a/AMWD.Protocols.Modbus.Common/README.md
+++ b/AMWD.Protocols.Modbus.Common/README.md
@@ -58,7 +58,7 @@ Here you have the specific default implementations for the Modbus Protocol.
- ASCII
- RTU
-- RTU over TCP _(in progress)_
+- RTU over TCP
- TCP
**NOTE:**
diff --git a/AMWD.Protocols.Modbus.Tests/Common/Protocols/RtuOverTcpProtocolTest.cs b/AMWD.Protocols.Modbus.Tests/Common/Protocols/RtuOverTcpProtocolTest.cs
new file mode 100644
index 0000000..debda2f
--- /dev/null
+++ b/AMWD.Protocols.Modbus.Tests/Common/Protocols/RtuOverTcpProtocolTest.cs
@@ -0,0 +1,1259 @@
+using System.Collections.Generic;
+using System.Reflection;
+using AMWD.Protocols.Modbus.Common.Protocols;
+
+namespace AMWD.Protocols.Modbus.Tests.Common.Protocols
+{
+ [TestClass]
+ public class RtuOverTcpProtocolTest
+ {
+ private const byte UNIT_ID = 0x2A; // 42
+
+ #region Read Coils
+
+ [TestMethod]
+ public void ShouldSerializeReadCoils()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var bytes = protocol.SerializeReadCoils(UNIT_ID, 19, 19);
+
+ // Assert
+ Assert.IsNotNull(bytes);
+ Assert.AreEqual(14, bytes.Count);
+
+ // Transaction id
+ Assert.AreEqual(0x00, bytes[0]);
+ Assert.AreEqual(0x01, bytes[1]);
+
+ // Protocol identifier
+ Assert.AreEqual(0x00, bytes[2]);
+ Assert.AreEqual(0x00, bytes[3]);
+
+ // Following bytes
+ Assert.AreEqual(0x00, bytes[4]);
+ Assert.AreEqual(0x08, bytes[5]);
+
+ // Unit id
+ Assert.AreEqual(UNIT_ID, bytes[6]);
+
+ // Function code
+ Assert.AreEqual(0x01, bytes[7]);
+
+ // Starting address
+ Assert.AreEqual(0x00, bytes[8]);
+ Assert.AreEqual(0x13, bytes[9]);
+ // Quantity
+ Assert.AreEqual(0x00, bytes[10]);
+ Assert.AreEqual(0x13, bytes[11]);
+
+ // CRC check will be ignored
+ }
+
+ [DataTestMethod]
+ [DataRow(0)]
+ [DataRow(2001)]
+ [ExpectedException(typeof(ArgumentOutOfRangeException))]
+ public void ShouldThrowOutOfRangeForCountOnSerializeReadCoils(int count)
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeReadCoils(UNIT_ID, 19, (ushort)count);
+
+ // Assert - ArgumentOutOfRangeException
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentOutOfRangeException))]
+ public void ShouldThrowOutOfRangeForStartingAddressOnSerializeReadCoils()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeReadCoils(UNIT_ID, ushort.MaxValue, 2);
+
+ // Assert - ArgumentOutOfRangeException
+ }
+
+ [TestMethod]
+ public void ShouldDeserializeReadCoils()
+ {
+ // Arrange
+ int[] setValues = [0, 2, 3, 6, 7, 8, 9, 11, 13, 14, 16, 18];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var coils = protocol.DeserializeReadCoils([0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x01, 0x03, 0xCD, 0x6B, 0x05, 0x00, 0x00]);
+
+ // Assert
+ Assert.IsNotNull(coils);
+ Assert.AreEqual(24, coils.Count);
+
+ for (int i = 0; i < 24; i++)
+ {
+ Assert.AreEqual(i, coils[i].Address);
+
+ if (setValues.Contains(i))
+ Assert.IsTrue(coils[i].Value);
+ else
+ Assert.IsFalse(coils[i].Value);
+ }
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowExceptionOnDeserializeReadCoils()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.DeserializeReadCoils([0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x01, 0x02, 0xCD, 0x6B, 0x05, 0x00, 0x00]);
+
+ // Assert - ModbusException
+ }
+
+ #endregion Read Coils
+
+ #region Read Discrete Inputs
+
+ [TestMethod]
+ public void ShouldSerializeReadDiscreteInputs()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var bytes = protocol.SerializeReadDiscreteInputs(UNIT_ID, 19, 19);
+
+ // Assert
+ Assert.IsNotNull(bytes);
+ Assert.AreEqual(14, bytes.Count);
+
+ // Transaction id
+ Assert.AreEqual(0x00, bytes[0]);
+ Assert.AreEqual(0x01, bytes[1]);
+
+ // Protocol identifier
+ Assert.AreEqual(0x00, bytes[2]);
+ Assert.AreEqual(0x00, bytes[3]);
+
+ // Following bytes
+ Assert.AreEqual(0x00, bytes[4]);
+ Assert.AreEqual(0x08, bytes[5]);
+
+ // Unit id
+ Assert.AreEqual(UNIT_ID, bytes[6]);
+
+ // Function code
+ Assert.AreEqual(0x02, bytes[7]);
+
+ // Starting address
+ Assert.AreEqual(0x00, bytes[8]);
+ Assert.AreEqual(0x13, bytes[9]);
+ // Quantity
+ Assert.AreEqual(0x00, bytes[10]);
+ Assert.AreEqual(0x13, bytes[11]);
+
+ // CRC check will be ignored
+ }
+
+ [DataTestMethod]
+ [DataRow(0)]
+ [DataRow(2001)]
+ [ExpectedException(typeof(ArgumentOutOfRangeException))]
+ public void ShouldThrowOutOfRangeForCountOnSerializeReadDiscreteInputs(int count)
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeReadDiscreteInputs(UNIT_ID, 19, (ushort)count);
+
+ // Assert - ArgumentOutOfRangeException
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentOutOfRangeException))]
+ public void ShouldThrowOutOfRangeForStartingAddressOnSerializeReadDiscreteInputs()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeReadDiscreteInputs(UNIT_ID, ushort.MaxValue, 2);
+
+ // Assert - ArgumentOutOfRangeException
+ }
+
+ [TestMethod]
+ public void ShouldDeserializeReadDiscreteInputs()
+ {
+ // Arrange
+ int[] setValues = [0, 2, 3, 6, 7, 8, 9, 11, 13, 14, 16, 18];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var discreteInputs = protocol.DeserializeReadDiscreteInputs([0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x02, 0x03, 0xCD, 0x6B, 0x05, 0x00, 0x00]);
+
+ // Assert
+ Assert.IsNotNull(discreteInputs);
+ Assert.AreEqual(24, discreteInputs.Count);
+
+ for (int i = 0; i < 24; i++)
+ {
+ Assert.AreEqual(i, discreteInputs[i].Address);
+
+ if (setValues.Contains(i))
+ Assert.IsTrue(discreteInputs[i].Value);
+ else
+ Assert.IsFalse(discreteInputs[i].Value);
+ }
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowExceptionOnDeserializeReadDiscreteInputs()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.DeserializeReadDiscreteInputs([0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x02, 0x02, 0xCD, 0x6B, 0x05, 0x00, 0x00]);
+
+ // Assert - ModbusException
+ }
+
+ #endregion Read Discrete Inputs
+
+ #region Read Holding Registers
+
+ [TestMethod]
+ public void ShouldSerializeReadHoldingRegisters()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var bytes = protocol.SerializeReadHoldingRegisters(UNIT_ID, 107, 2);
+
+ // Assert
+ Assert.IsNotNull(bytes);
+ Assert.AreEqual(14, bytes.Count);
+
+ // Transaction id
+ Assert.AreEqual(0x00, bytes[0]);
+ Assert.AreEqual(0x01, bytes[1]);
+
+ // Protocol identifier
+ Assert.AreEqual(0x00, bytes[2]);
+ Assert.AreEqual(0x00, bytes[3]);
+
+ // Following bytes
+ Assert.AreEqual(0x00, bytes[4]);
+ Assert.AreEqual(0x08, bytes[5]);
+
+ // Unit id
+ Assert.AreEqual(UNIT_ID, bytes[6]);
+
+ // Function code
+ Assert.AreEqual(0x03, bytes[7]);
+
+ // Starting address
+ Assert.AreEqual(0x00, bytes[8]);
+ Assert.AreEqual(0x6B, bytes[9]);
+ // Quantity
+ Assert.AreEqual(0x00, bytes[10]);
+ Assert.AreEqual(0x02, bytes[11]);
+
+ // CRC check will be ignored
+ }
+
+ [DataTestMethod]
+ [DataRow(0)]
+ [DataRow(126)]
+ [ExpectedException(typeof(ArgumentOutOfRangeException))]
+ public void ShouldThrowOutOfRangeForCountOnSerializeReadHoldingRegisters(int count)
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeReadHoldingRegisters(UNIT_ID, 19, (ushort)count);
+
+ // Assert - ArgumentOutOfRangeException
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentOutOfRangeException))]
+ public void ShouldThrowOutOfRangeForStartingAddressOnSerializeReadHoldingRegisters()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeReadHoldingRegisters(UNIT_ID, ushort.MaxValue, 2);
+
+ // Assert - ArgumentOutOfRangeException
+ }
+
+ [TestMethod]
+ public void ShouldDeserializeReadHoldingRegisters()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var registers = protocol.DeserializeReadHoldingRegisters([0x00, 0x01, 0x00, 0x00, 0x00, 0x09, UNIT_ID, 0x03, 0x04, 0x02, 0x2B, 0x00, 0x64, 0x00, 0x00]);
+
+ // Assert
+ Assert.IsNotNull(registers);
+ Assert.AreEqual(2, registers.Count);
+
+ Assert.AreEqual(0, registers[0].Address);
+ Assert.AreEqual(555, registers[0].Value);
+
+ Assert.AreEqual(1, registers[1].Address);
+ Assert.AreEqual(100, registers[1].Value);
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowExceptionOnDeserializeReadHoldingRegisters()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.DeserializeReadHoldingRegisters([0x00, 0x01, 0x00, 0x00, 0x00, 0x07, UNIT_ID, 0x03, 0x04, 0x02, 0x2B, 0x00, 0x00]);
+
+ // Assert - ModbusException
+ }
+
+ #endregion Read Holding Registers
+
+ #region Read Input Registers
+
+ [TestMethod]
+ public void ShouldSerializeReadInputRegisters()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var bytes = protocol.SerializeReadInputRegisters(UNIT_ID, 107, 2);
+
+ // Assert
+ Assert.IsNotNull(bytes);
+ Assert.AreEqual(14, bytes.Count);
+
+ // Transaction id
+ Assert.AreEqual(0x00, bytes[0]);
+ Assert.AreEqual(0x01, bytes[1]);
+
+ // Protocol identifier
+ Assert.AreEqual(0x00, bytes[2]);
+ Assert.AreEqual(0x00, bytes[3]);
+
+ // Following bytes
+ Assert.AreEqual(0x00, bytes[4]);
+ Assert.AreEqual(0x08, bytes[5]);
+
+ // Unit id
+ Assert.AreEqual(UNIT_ID, bytes[6]);
+
+ // Function code
+ Assert.AreEqual(0x04, bytes[7]);
+
+ // Starting address
+ Assert.AreEqual(0x00, bytes[8]);
+ Assert.AreEqual(0x6B, bytes[9]);
+ // Quantity
+ Assert.AreEqual(0x00, bytes[10]);
+ Assert.AreEqual(0x02, bytes[11]);
+
+ // CRC check will be ignored
+ }
+
+ [DataTestMethod]
+ [DataRow(0)]
+ [DataRow(126)]
+ [ExpectedException(typeof(ArgumentOutOfRangeException))]
+ public void ShouldThrowOutOfRangeForCountOnSerializeReadInputRegisters(int count)
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeReadInputRegisters(UNIT_ID, 19, (ushort)count);
+
+ // Assert - ArgumentOutOfRangeException
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentOutOfRangeException))]
+ public void ShouldThrowOutOfRangeForStartingAddressOnSerializeReadInputRegisters()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeReadInputRegisters(UNIT_ID, ushort.MaxValue, 2);
+
+ // Assert - ArgumentOutOfRangeException
+ }
+
+ [TestMethod]
+ public void ShouldDeserializeReadInputRegisters()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var registers = protocol.DeserializeReadInputRegisters([0x00, 0x01, 0x00, 0x00, 0x00, 0x09, UNIT_ID, 0x04, 0x04, 0x02, 0x2B, 0x00, 0x64, 0x00, 0x00]);
+
+ // Assert
+ Assert.IsNotNull(registers);
+ Assert.AreEqual(2, registers.Count);
+
+ Assert.AreEqual(0, registers[0].Address);
+ Assert.AreEqual(555, registers[0].Value);
+
+ Assert.AreEqual(1, registers[1].Address);
+ Assert.AreEqual(100, registers[1].Value);
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowExceptionOnDeserializeReadInputRegisters()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.DeserializeReadInputRegisters([0x00, 0x01, 0x00, 0x00, 0x00, 0x07, UNIT_ID, 0x04, 0x04, 0x02, 0x2B, 0x00, 0x00]);
+
+ // Assert - ModbusException
+ }
+
+ #endregion Read Input Registers
+
+ #region Read Device Identification
+
+ [DataTestMethod]
+ [DataRow(ModbusDeviceIdentificationCategory.Basic)]
+ [DataRow(ModbusDeviceIdentificationCategory.Regular)]
+ [DataRow(ModbusDeviceIdentificationCategory.Extended)]
+ [DataRow(ModbusDeviceIdentificationCategory.Individual)]
+ public void ShouldSerializeReadDeviceIdentification(ModbusDeviceIdentificationCategory category)
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var bytes = protocol.SerializeReadDeviceIdentification(UNIT_ID, category, ModbusDeviceIdentificationObject.ProductCode);
+
+ // Assert
+ Assert.IsNotNull(bytes);
+ Assert.AreEqual(13, bytes.Count);
+
+ // Transaction id
+ Assert.AreEqual(0x00, bytes[0]);
+ Assert.AreEqual(0x01, bytes[1]);
+
+ // Protocol identifier
+ Assert.AreEqual(0x00, bytes[2]);
+ Assert.AreEqual(0x00, bytes[3]);
+
+ // Following bytes
+ Assert.AreEqual(0x00, bytes[4]);
+ Assert.AreEqual(0x07, bytes[5]);
+
+ // Unit id
+ Assert.AreEqual(UNIT_ID, bytes[6]);
+
+ // Function code
+ Assert.AreEqual(0x2B, bytes[7]);
+
+ // MEI Type
+ Assert.AreEqual(0x0E, bytes[8]);
+
+ // Category
+ Assert.AreEqual((byte)category, bytes[9]);
+
+ // Object Id
+ Assert.AreEqual((byte)ModbusDeviceIdentificationObject.ProductCode, bytes[10]);
+
+ // CRC check will be ignored
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentOutOfRangeException))]
+ public void ShouldThrowOutOfRangeExceptionForCategoryOnSerializeReadDeviceIdentification()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeReadDeviceIdentification(UNIT_ID, (ModbusDeviceIdentificationCategory)10, ModbusDeviceIdentificationObject.ProductCode);
+
+ // Assert - ArgumentOutOfRangeException
+ }
+
+ [DataTestMethod]
+ [DataRow(false)]
+ [DataRow(true)]
+ public void ShouldDeserializeReadDeviceIdentification(bool moreAndIndividual)
+ {
+ // Arrange
+ byte[] response = [0x00, 0x01, 0x00, 0x00, 0x00, 0x0E, UNIT_ID, 0x2B, 0x0E, 0x02, (byte)(moreAndIndividual ? 0x82 : 0x02), (byte)(moreAndIndividual ? 0xFF : 0x00), (byte)(moreAndIndividual ? 0x05 : 0x00), 0x01, 0x04, 0x02, 0x41, 0x4D, 0x00, 0x00];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var result = protocol.DeserializeReadDeviceIdentification(response);
+
+ // Assert
+ Assert.IsNotNull(result);
+ Assert.AreEqual(moreAndIndividual, result.AllowsIndividualAccess);
+ Assert.AreEqual(moreAndIndividual, result.MoreRequestsNeeded);
+ Assert.AreEqual(moreAndIndividual ? 0x05 : 0x00, result.NextObjectIdToRequest);
+
+ Assert.AreEqual(1, result.Objects.Count);
+ Assert.AreEqual(4, result.Objects.First().Key);
+ CollectionAssert.AreEqual("AM"u8.ToArray(), result.Objects.First().Value);
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowExceptionOnDeserializeReadDeviceIdentificationForMeiType()
+ {
+ // Arrange
+ byte[] response = [0x00, 0x01, 0x00, 0x00, 0x00, 0x05, UNIT_ID, 0x2B, 0x0D, 0x00, 0x00];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.DeserializeReadDeviceIdentification(response);
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowExceptionOnDeserializeReadDeviceIdentificationForCategory()
+ {
+ // Arrange
+ byte[] response = [0x00, 0x01, 0x00, 0x00, 0x00, 0x06, UNIT_ID, 0x2B, 0x0E, 0x08, 0x00, 0x00];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.DeserializeReadDeviceIdentification(response);
+ }
+
+ #endregion Read Device Identification
+
+ #region Write Single Coil
+
+ [TestMethod]
+ public void ShouldSerializeWriteSingleCoil()
+ {
+ // Arrange
+ var coil = new Coil { Address = 109, Value = true };
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var result = protocol.SerializeWriteSingleCoil(UNIT_ID, coil);
+
+ // Assert
+ Assert.IsNotNull(result);
+ Assert.AreEqual(14, result.Count);
+
+ // Transaction id
+ Assert.AreEqual(0x00, result[0]);
+ Assert.AreEqual(0x01, result[1]);
+
+ // Protocol identifier
+ Assert.AreEqual(0x00, result[2]);
+ Assert.AreEqual(0x00, result[3]);
+
+ // Following bytes
+ Assert.AreEqual(0x00, result[4]);
+ Assert.AreEqual(0x08, result[5]);
+
+ // Unit id
+ Assert.AreEqual(UNIT_ID, result[6]);
+
+ // Function code
+ Assert.AreEqual(0x05, result[7]);
+
+ // Starting address
+ Assert.AreEqual(0x00, result[8]);
+ Assert.AreEqual(0x6D, result[9]);
+
+ // Value
+ Assert.AreEqual(0xFF, result[10]);
+ Assert.AreEqual(0x00, result[11]);
+
+ // CRC check will be ignored
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentNullException))]
+ public void ShouldThrowArgumentNullOnSerializeWriteSingleCoil()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeWriteSingleCoil(UNIT_ID, null);
+
+ // Assert - ArgumentNullException
+ }
+
+ [TestMethod]
+ public void ShouldDeserializeWriteSingleCoil()
+ {
+ // Arrange
+ byte[] bytes = [0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x05, 0x01, 0x0A, 0xFF, 0x00, 0x00, 0x00];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var coil = protocol.DeserializeWriteSingleCoil(bytes);
+
+ // Assert
+ Assert.IsNotNull(coil);
+ Assert.AreEqual(266, coil.Address);
+ Assert.IsTrue(coil.Value);
+ }
+
+ #endregion Write Single Coil
+
+ #region Write Single Register
+
+ [TestMethod]
+ public void ShouldSerializeWriteSingleHoldingRegister()
+ {
+ // Arrange
+ var register = new HoldingRegister { Address = 109, Value = 123 };
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var result = protocol.SerializeWriteSingleHoldingRegister(UNIT_ID, register);
+
+ // Assert
+ Assert.IsNotNull(result);
+ Assert.AreEqual(14, result.Count);
+
+ // Transaction id
+ Assert.AreEqual(0x00, result[0]);
+ Assert.AreEqual(0x01, result[1]);
+
+ // Protocol identifier
+ Assert.AreEqual(0x00, result[2]);
+ Assert.AreEqual(0x00, result[3]);
+
+ // Following bytes
+ Assert.AreEqual(0x00, result[4]);
+ Assert.AreEqual(0x08, result[5]);
+
+ // Unit id
+ Assert.AreEqual(UNIT_ID, result[6]);
+
+ // Function code
+ Assert.AreEqual(0x06, result[7]);
+
+ // Starting address
+ Assert.AreEqual(0x00, result[8]);
+ Assert.AreEqual(0x6D, result[9]);
+
+ // Value
+ Assert.AreEqual(0x00, result[10]);
+ Assert.AreEqual(0x7B, result[11]);
+
+ // CRC check will be ignored
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentNullException))]
+ public void ShouldThrowArgumentNullOnSerializeWriteSingleHoldingRegister()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeWriteSingleHoldingRegister(UNIT_ID, null);
+
+ // Assert - ArgumentNullException
+ }
+
+ [TestMethod]
+ public void ShouldDeserializeWriteSingleHoldingRegister()
+ {
+ // Arrange
+ byte[] bytes = [0x00, 0x01, 0x00, 0x00, 0x00, 0x06, 0x2A, 0x06, 0x02, 0x02, 0x01, 0x23, 0x00, 0x00];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var register = protocol.DeserializeWriteSingleHoldingRegister(bytes);
+
+ // Assert
+ Assert.IsNotNull(register);
+ Assert.AreEqual(514, register.Address);
+ Assert.AreEqual(291, register.Value);
+ }
+
+ #endregion Write Single Register
+
+ #region Write Multiple Coils
+
+ [TestMethod]
+ public void ShouldSerializeWriteMultipleCoils()
+ {
+ // Arrange
+ var coils = new Coil[]
+ {
+ new() { Address = 10, Value = true },
+ new() { Address = 11, Value = false },
+ new() { Address = 12, Value = true },
+ new() { Address = 13, Value = false },
+ new() { Address = 14, Value = true },
+ };
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var result = protocol.SerializeWriteMultipleCoils(UNIT_ID, coils);
+
+ // Assert
+ Assert.IsNotNull(result);
+ Assert.AreEqual(16, result.Count);
+
+ // Transaction id
+ Assert.AreEqual(0x00, result[0]);
+ Assert.AreEqual(0x01, result[1]);
+
+ // Protocol identifier
+ Assert.AreEqual(0x00, result[2]);
+ Assert.AreEqual(0x00, result[3]);
+
+ // Following bytes
+ Assert.AreEqual(0x00, result[4]);
+ Assert.AreEqual(0x0A, result[5]);
+
+ // Unit id
+ Assert.AreEqual(UNIT_ID, result[6]);
+
+ // Function code
+ Assert.AreEqual(0x0F, result[7]);
+
+ // Starting address
+ Assert.AreEqual(0x00, result[8]);
+ Assert.AreEqual(0x0A, result[9]);
+
+ // Quantity
+ Assert.AreEqual(0x00, result[10]);
+ Assert.AreEqual(0x05, result[11]);
+
+ // Byte count
+ Assert.AreEqual(0x01, result[12]);
+
+ // Values
+ Assert.AreEqual(0x15, result[13]);
+
+ // CRC check will be ignored
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentNullException))]
+ public void ShouldThrowArgumentNullOnSerializeWriteMultipleCoils()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeWriteMultipleCoils(UNIT_ID, null);
+
+ // Assert - ArgumentNullException
+ }
+
+ [DataTestMethod]
+ [DataRow(0)]
+ [DataRow(1969)]
+ [ExpectedException(typeof(ArgumentOutOfRangeException))]
+ public void ShouldThrowOutOfRangeForCountOnSerializeWriteMultipleCoils(int count)
+ {
+ // Arrange
+ var coils = new List();
+ for (int i = 0; i < count; i++)
+ coils.Add(new() { Address = (ushort)i });
+
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeWriteMultipleCoils(UNIT_ID, coils);
+
+ // Assert - ArgumentOutOfRangeException
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentException))]
+ public void ShouldThrowArgumentExceptionForDuplicateEntryOnSerializeMultipleCoils()
+ {
+ // Arrange
+ var coils = new Coil[]
+ {
+ new() { Address = 10, Value = true },
+ new() { Address = 10, Value = false },
+ };
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeWriteMultipleCoils(UNIT_ID, coils);
+
+ // Assert - ArgumentException
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentException))]
+ public void ShouldThrowArgumentExceptionForGapInAddressOnSerializeMultipleCoils()
+ {
+ // Arrange
+ var coils = new Coil[]
+ {
+ new() { Address = 10, Value = true },
+ new() { Address = 12, Value = false },
+ };
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeWriteMultipleCoils(UNIT_ID, coils);
+
+ // Assert - ArgumentException
+ }
+
+ [TestMethod]
+ public void ShouldDeserializeWriteMultipleCoils()
+ {
+ // Arrange
+ byte[] bytes = [0x00, 0x01, 0x00, 0x00, 0x00, 0x06, 0x2A, 0x0F, 0x01, 0x0A, 0x00, 0x0B, 0x00, 0x00];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var (firstAddress, numberOfCoils) = protocol.DeserializeWriteMultipleCoils(bytes);
+
+ // Assert
+ Assert.AreEqual(266, firstAddress);
+ Assert.AreEqual(11, numberOfCoils);
+ }
+
+ #endregion Write Multiple Coils
+
+ #region Write Multiple Holding Registers
+
+ [TestMethod]
+ public void ShouldSerializeWriteMultipleHoldingRegisters()
+ {
+ // Arrange
+ var registers = new HoldingRegister[]
+ {
+ new() { Address = 10, Value = 10 },
+ new() { Address = 11, Value = 11 }
+ };
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var result = protocol.SerializeWriteMultipleHoldingRegisters(UNIT_ID, registers);
+
+ // Assert
+ Assert.IsNotNull(result);
+ Assert.AreEqual(19, result.Count);
+
+ // Transaction id
+ Assert.AreEqual(0x00, result[0]);
+ Assert.AreEqual(0x01, result[1]);
+
+ // Protocol identifier
+ Assert.AreEqual(0x00, result[2]);
+ Assert.AreEqual(0x00, result[3]);
+
+ // Following bytes
+ Assert.AreEqual(0x00, result[4]);
+ Assert.AreEqual(0x0D, result[5]);
+
+ // Unit id
+ Assert.AreEqual(UNIT_ID, result[6]);
+
+ // Function code
+ Assert.AreEqual(0x10, result[7]);
+
+ // Starting address
+ Assert.AreEqual(0x00, result[8]);
+ Assert.AreEqual(0x0A, result[9]);
+
+ // Quantity
+ Assert.AreEqual(0x00, result[10]);
+ Assert.AreEqual(0x02, result[11]);
+
+ // Byte count
+ Assert.AreEqual(0x04, result[12]);
+
+ // Values
+ Assert.AreEqual(0x00, result[13]);
+ Assert.AreEqual(0x0A, result[14]);
+ Assert.AreEqual(0x00, result[15]);
+ Assert.AreEqual(0x0B, result[16]);
+
+ // CRC check will be ignored
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentNullException))]
+ public void ShouldThrowArgumentNullOnSerializeWriteMultipleHoldingRegisters()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeWriteMultipleHoldingRegisters(UNIT_ID, null);
+
+ // Assert - ArgumentNullException
+ }
+
+ [DataTestMethod]
+ [DataRow(0)]
+ [DataRow(124)]
+ [ExpectedException(typeof(ArgumentOutOfRangeException))]
+ public void ShouldThrowOutOfRangeForCountOnSerializeWriteMultipleHoldingRegisters(int count)
+ {
+ // Arrange
+ var registers = new List();
+ for (int i = 0; i < count; i++)
+ registers.Add(new() { Address = (ushort)i });
+
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeWriteMultipleHoldingRegisters(UNIT_ID, registers);
+
+ // Assert - ArgumentOutOfRangeException
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentException))]
+ public void ShouldThrowArgumentExceptionForDuplicateEntryOnSerializeMultipleHoldingRegisters()
+ {
+ // Arrange
+ var registers = new HoldingRegister[]
+ {
+ new() { Address = 10 },
+ new() { Address = 10 },
+ };
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeWriteMultipleHoldingRegisters(UNIT_ID, registers);
+
+ // Assert - ArgumentException
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ArgumentException))]
+ public void ShouldThrowArgumentExceptionForGapInAddressOnSerializeMultipleHoldingRegisters()
+ {
+ // Arrange
+ var registers = new HoldingRegister[]
+ {
+ new() { Address = 10 },
+ new() { Address = 12 },
+ };
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.SerializeWriteMultipleHoldingRegisters(UNIT_ID, registers);
+
+ // Assert - ArgumentException
+ }
+
+ [TestMethod]
+ public void ShouldDeserializeWriteMultipleHoldingRegisters()
+ {
+ // Arrange
+ byte[] bytes = [0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x10, 0x02, 0x0A, 0x00, 0x0A, 0x00, 0x00];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ var (firstAddress, numberOfCoils) = protocol.DeserializeWriteMultipleHoldingRegisters(bytes);
+
+ // Assert
+ Assert.AreEqual(522, firstAddress);
+ Assert.AreEqual(10, numberOfCoils);
+ }
+
+ #endregion Write Multiple Holding Registers
+
+ #region Validation
+
+ [TestMethod]
+ public void ShouldReturnFalseForMinLengthOnCheckResponseComplete()
+ {
+ // Arrange
+ byte[] bytes = [0x00, 0x01, 0x00];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ bool complete = protocol.CheckResponseComplete(bytes);
+
+ // Assert
+ Assert.IsFalse(complete);
+ }
+
+ [TestMethod]
+ public void ShouldReturnFalseForFollowingBytesOnCheckResponseComplete()
+ {
+ // Arrange
+ byte[] bytes = [0x00, 0x01, 0x00, 0x00, 0x00, 0x02, 0x81];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ bool complete = protocol.CheckResponseComplete(bytes);
+
+ // Assert
+ Assert.IsFalse(complete);
+ }
+
+ [TestMethod]
+ public void ShouldReturnTrueOnCheckResponseComplete()
+ {
+ // Arrange
+ byte[] bytes = [0x00, 0x01, 0x00, 0x00, 0x00, 0x02, 0x81, 0x01];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ bool complete = protocol.CheckResponseComplete(bytes);
+
+ // Assert
+ Assert.IsTrue(complete);
+ }
+
+ [TestMethod]
+ public void ShouldValidateResponse()
+ {
+ // Arrange
+ byte[] request = [0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x01, 0x00, 0x01, 0x00, 0x02, 0x00, 0x00];
+ byte[] response = [0x00, 0x01, 0x00, 0x00, 0x00, 0x06, UNIT_ID, 0x01, 0x01, 0x00, 0x00, 0x00];
+ SetCrc(response);
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.ValidateResponse(request, response);
+ }
+
+ [TestMethod]
+ public void ShouldValidateResponseIgnoringTransactionId()
+ {
+ // Arrange
+ byte[] request = [0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x01, 0x00, 0x01, 0x00, 0x02, 0x00, 0x00];
+ byte[] response = [0x00, 0x00, 0x00, 0x00, 0x00, 0x06, UNIT_ID, 0x01, 0x01, 0x00, 0x00, 0x00];
+ SetCrc(response);
+ var protocol = new RtuOverTcpProtocol { DisableTransactionId = true };
+
+ // Act
+ protocol.ValidateResponse(request, response);
+ }
+
+ [DataTestMethod]
+ [DataRow(0x00, 0x00)]
+ [DataRow(0x01, 0x01)]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowForTransactionIdOnValidateResponse(int hi, int lo)
+ {
+ // Arrange
+ byte[] request = [(byte)hi, (byte)lo, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x01, 0x00, 0x01, 0x00, 0x02, 0x00, 0x00];
+ byte[] response = [0x00, 0x01, 0x00, 0x00, 0x00, 0x06, UNIT_ID, 0x01, 0x01, 0x00, 0x00, 0x00];
+ SetCrc(response);
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.ValidateResponse(request, response);
+ }
+
+ [DataTestMethod]
+ [DataRow(0x00, 0x01)]
+ [DataRow(0x01, 0x00)]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowForProtocolIdOnValidateResponse(int hi, int lo)
+ {
+ // Arrange
+ byte[] request = [0x00, 0x01, (byte)hi, (byte)lo, 0x00, 0x08, UNIT_ID, 0x01, 0x00, 0x01, 0x00, 0x02, 0x00, 0x00];
+ byte[] response = [0x00, 0x01, 0x00, 0x00, 0x00, 0x06, UNIT_ID, 0x01, 0x01, 0x00, 0x00, 0x00];
+ SetCrc(response);
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.ValidateResponse(request, response);
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowForFollowingBytesOnValidateResponse()
+ {
+ // Arrange
+ byte[] request = [0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x01, 0x00, 0x01, 0x00, 0x02, 0x00, 0x00];
+ byte[] response = [0x00, 0x01, 0x00, 0x00, 0x00, 0x07, UNIT_ID, 0x01, 0x01, 0x00, 0x00, 0x00];
+ SetCrc(response);
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.ValidateResponse(request, response);
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowForUnitIdOnValidateResponse()
+ {
+ // Arrange
+ byte[] request = [0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x01, 0x00, 0x01, 0x00, 0x02, 0x00, 0x00];
+ byte[] response = [0x00, 0x01, 0x00, 0x00, 0x00, 0x06, UNIT_ID + 1, 0x01, 0x01, 0x00, 0x00, 0x00];
+ SetCrc(response);
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.ValidateResponse(request, response);
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowForFunctionCodeOnValidateResponse()
+ {
+ // Arrange
+ byte[] request = [0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x01, 0x00, 0x01, 0x00, 0x02, 0x00, 0x00];
+ byte[] response = [0x00, 0x01, 0x00, 0x00, 0x00, 0x06, UNIT_ID, 0x02, 0x01, 0x00, 0x00, 0x00];
+ SetCrc(response);
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.ValidateResponse(request, response);
+ }
+
+ [TestMethod]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowForModbusErrorOnValidateResponse()
+ {
+ // Arrange
+ byte[] request = [0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x01, 0x00, 0x01, 0x00, 0x02, 0x00, 0x00];
+ byte[] response = [0x00, 0x01, 0x00, 0x00, 0x00, 0x05, UNIT_ID, 0x81, 0x01, 0x00, 0x00];
+ SetCrc(response);
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.ValidateResponse(request, response);
+ }
+
+ [DataTestMethod]
+ [DataRow(0x59, 0x6C)]
+ [DataRow(0x58, 0x6B)]
+ [ExpectedException(typeof(ModbusException))]
+ public void ShouldThrowForCrcOnValidateResponse(int hi, int lo)
+ {
+ // Arrange
+ byte[] request = [0x00, 0x01, 0x00, 0x00, 0x00, 0x08, UNIT_ID, 0x01, 0x00, 0x01, 0x00, 0x02, 0x00, 0x00];
+ byte[] response = [0x00, 0x01, 0x00, 0x00, 0x00, 0x06, UNIT_ID, 0x01, 0x01, 0x00, (byte)hi, (byte)lo];
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ protocol.ValidateResponse(request, response);
+ }
+
+ #endregion Validation
+
+ #region Helper
+
+ [TestMethod]
+ public void ShouldIncreaseTransactionId()
+ {
+ // Arrange
+ var list = new List();
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ list.Add([.. protocol.SerializeReadCoils(UNIT_ID, 10, 10)]);
+ list.Add([.. protocol.SerializeReadCoils(UNIT_ID, 10, 10)]);
+ list.Add([.. protocol.SerializeReadCoils(UNIT_ID, 10, 10)]);
+
+ // Assert
+ for (int i = 0; i < list.Count; i++)
+ {
+ Assert.AreEqual(0x00, list[i][0]);
+ Assert.AreEqual((byte)(i + 1), list[i][1]);
+
+ // Other asserts already done
+ }
+ }
+
+ [TestMethod]
+ public void ShouldNotIncreaseTransactionId()
+ {
+ // Arrange
+ var list = new List();
+ var protocol = new RtuOverTcpProtocol { DisableTransactionId = true };
+
+ // Act
+ list.Add([.. protocol.SerializeReadCoils(UNIT_ID, 10, 10)]);
+ list.Add([.. protocol.SerializeReadCoils(UNIT_ID, 10, 10)]);
+ list.Add([.. protocol.SerializeReadCoils(UNIT_ID, 10, 10)]);
+
+ // Assert
+ for (int i = 0; i < list.Count; i++)
+ {
+ Assert.AreEqual(0x00, list[i][0]);
+ Assert.AreEqual(0x00, list[i][1]);
+
+ // Other asserts already done
+ }
+ }
+
+ [TestMethod]
+ public void ShouldResetTransactionIdOnMaxValue()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+ protocol.GetType()
+ .GetField("_transactionId", BindingFlags.NonPublic | BindingFlags.Instance)
+ .SetValue(protocol, (ushort)(ushort.MaxValue - 1));
+
+ // Act
+ var result1 = protocol.SerializeReadCoils(UNIT_ID, 10, 10);
+ var result2 = protocol.SerializeReadCoils(UNIT_ID, 10, 10);
+
+ // Assert
+ Assert.AreEqual(0xFF, result1[0]);
+ Assert.AreEqual(0xFF, result1[1]);
+
+ Assert.AreEqual(0x00, result2[0]);
+ Assert.AreEqual(0x00, result2[1]);
+ }
+
+ #endregion Helper
+
+ [TestMethod]
+ public void ShouldNameRtuOverTcp()
+ {
+ // Arrange
+ var protocol = new RtuOverTcpProtocol();
+
+ // Act
+ string result = protocol.Name;
+
+ // Assert
+ Assert.AreEqual("RTU over TCP", result);
+ }
+
+ private static void SetCrc(byte[] bytes)
+ {
+ byte[] crc = RtuProtocol.CRC16(bytes, 6, bytes.Length - 8);
+ bytes[^2] = crc[0];
+ bytes[^1] = crc[1];
+ }
+ }
+}