Implementing ASCII protocol; removing min. unit ID for serial line - see note on README
This commit is contained in:
733
AMWD.Protocols.Modbus.Common/Protocols/AsciiProtocol.cs
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733
AMWD.Protocols.Modbus.Common/Protocols/AsciiProtocol.cs
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using AMWD.Protocols.Modbus.Common.Contracts;
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namespace AMWD.Protocols.Modbus.Common.Protocols
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{
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/// <summary>
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/// Default implementation of the Modbus ASCII protocol.
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/// </summary>
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public class AsciiProtocol : IModbusProtocol
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{
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#region Constants
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/// <summary>
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/// The minimum allowed unit id specified by the Modbus SerialLine protocol.
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/// </summary>
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/// <remarks>
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/// <strong>INFORMATION:</strong>
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/// <br/>
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/// Reading the specification, the minimum allowed unit ID would be <strong>1</strong>.
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/// <br/>
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/// As of other implementations seen, this limit is <em>not</em> enforced!
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/// </remarks>
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public const byte MIN_UNIT_ID = 0x01;
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/// <summary>
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/// The maximum allowed unit id specified by the Modbus SerialLine protocol.
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/// </summary>
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/// <remarks>
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/// Reading the specification, the max allowed unit id would be <strong>247</strong>!
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/// </remarks>
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public const byte MAX_UNIT_ID = 0xFF;
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/// <summary>
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/// The minimum allowed read count specified by the Modbus SerialLine protocol.
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/// </summary>
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public const ushort MIN_READ_COUNT = 0x01;
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/// <summary>
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/// The minimum allowed write count specified by the Modbus SerialLine protocol.
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/// </summary>
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public const ushort MIN_WRITE_COUNT = 0x01;
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/// <summary>
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/// The maximum allowed read count for discrete values specified by the Modbus SerialLine protocol.
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/// </summary>
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public const ushort MAX_DISCRETE_READ_COUNT = 0x07D0; // 2000
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/// <summary>
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/// The maximum allowed write count for discrete values specified by the Modbus SerialLine protocol.
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/// </summary>
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public const ushort MAX_DISCRETE_WRITE_COUNT = 0x07B0; // 1968
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/// <summary>
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/// The maximum allowed read count for registers specified by the Modbus SerialLine protocol.
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/// </summary>
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public const ushort MAX_REGISTER_READ_COUNT = 0x007D; // 125
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/// <summary>
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/// The maximum allowed write count for registers specified by the Modbus SerialLine protocol.
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/// </summary>
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public const ushort MAX_REGISTER_WRITE_COUNT = 0x007B; // 123
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/// <summary>
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/// The maximum allowed ADU length in chars.
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/// </summary>
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/// <remarks>
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/// A Modbus frame consists of a PDU (protcol data unit) and additional protocol addressing / error checks.
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/// The whole data frame is called ADU (application data unit).
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/// </remarks>
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public const int MAX_ADU_LENGTH = 513; // chars in ASCII (so bytes in the end)
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#endregion Constants
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/// <inheritdoc/>
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public string Name => "ASCII";
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#region Read
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/// <inheritdoc/>
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public IReadOnlyList<byte> SerializeReadCoils(byte unitId, ushort startAddress, ushort count)
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{
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if (count < MIN_READ_COUNT || MAX_DISCRETE_READ_COUNT < count)
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throw new ArgumentOutOfRangeException(nameof(count));
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if (ushort.MaxValue < (startAddress + count - 1))
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throw new ArgumentOutOfRangeException(nameof(count), $"Combination of {nameof(startAddress)} and {nameof(count)} exceeds the addressation limit of {ushort.MaxValue}");
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// Unit Id and Function code
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string request = $":{unitId:X2}{(byte)ModbusFunctionCode.ReadCoils:X2}";
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// Starting address
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byte[] addrBytes = startAddress.ToBigEndianBytes();
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request += $"{addrBytes[0]:X2}{addrBytes[1]:X2}";
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// Quantity
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byte[] countBytes = count.ToBigEndianBytes();
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request += $"{countBytes[0]:X2}{countBytes[1]:X2}";
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// LRC
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string lrc = LRC(request);
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request += lrc;
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// CRLF
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request += "\r\n";
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return Encoding.ASCII.GetBytes(request);
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}
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/// <inheritdoc/>
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public IReadOnlyList<Coil> DeserializeReadCoils(IReadOnlyList<byte> response)
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{
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string responseMessage = Encoding.ASCII.GetString([.. response]).ToUpper();
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byte numBytes = HexToByte(responseMessage.Substring(5, 2));
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byte[] responsePayloadBytes = HexStringToByteArray(responseMessage.Substring(7, responseMessage.Length - 11));
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if (numBytes != responsePayloadBytes.Length)
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throw new ModbusException("Coil byte count does not match.");
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int count = numBytes * 8;
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var coils = new List<Coil>();
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for (int i = 0; i < count; i++)
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{
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int bytePosition = i / 8;
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int bitPosition = i % 8;
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int value = responsePayloadBytes[bytePosition] & (1 << bitPosition);
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coils.Add(new Coil
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{
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Address = (ushort)i,
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Value = value > 0
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});
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}
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return coils;
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}
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/// <inheritdoc/>
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public IReadOnlyList<byte> SerializeReadDiscreteInputs(byte unitId, ushort startAddress, ushort count)
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{
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if (count < MIN_READ_COUNT || MAX_DISCRETE_READ_COUNT < count)
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throw new ArgumentOutOfRangeException(nameof(count));
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if (ushort.MaxValue < (startAddress + count - 1))
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throw new ArgumentOutOfRangeException(nameof(count), $"Combination of {nameof(startAddress)} and {nameof(count)} exceeds the addressation limit of {ushort.MaxValue}");
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// Unit Id and Function code
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string request = $":{unitId:X2}{(byte)ModbusFunctionCode.ReadDiscreteInputs:X2}";
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// Starting address
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byte[] addrBytes = startAddress.ToBigEndianBytes();
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request += $"{addrBytes[0]:X2}{addrBytes[1]:X2}";
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// Quantity
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byte[] countBytes = count.ToBigEndianBytes();
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request += $"{countBytes[0]:X2}{countBytes[1]:X2}";
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// LRC
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string lrc = LRC(request);
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request += lrc;
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// CRLF
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request += "\r\n";
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return Encoding.ASCII.GetBytes(request);
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}
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/// <inheritdoc/>
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public IReadOnlyList<DiscreteInput> DeserializeReadDiscreteInputs(IReadOnlyList<byte> response)
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{
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string responseMessage = Encoding.ASCII.GetString([.. response]).ToUpper();
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byte numBytes = HexToByte(responseMessage.Substring(5, 2));
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byte[] responsePayloadBytes = HexStringToByteArray(responseMessage.Substring(7, responseMessage.Length - 11));
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if (numBytes != responsePayloadBytes.Length)
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throw new ModbusException("Discrete input byte count does not match.");
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int count = numBytes * 8;
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var discreteInputs = new List<DiscreteInput>();
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for (int i = 0; i < count; i++)
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{
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int bytePosition = i / 8;
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int bitPosition = i % 8;
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int value = responsePayloadBytes[bytePosition] & (1 << bitPosition);
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discreteInputs.Add(new DiscreteInput
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{
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Address = (ushort)i,
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HighByte = (byte)(value > 0 ? 0xFF : 0x00)
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});
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}
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return discreteInputs;
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}
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/// <inheritdoc/>
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public IReadOnlyList<byte> SerializeReadHoldingRegisters(byte unitId, ushort startAddress, ushort count)
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{
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if (count < MIN_READ_COUNT || MAX_REGISTER_READ_COUNT < count)
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throw new ArgumentOutOfRangeException(nameof(count));
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if (ushort.MaxValue < (startAddress + count - 1))
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throw new ArgumentOutOfRangeException(nameof(count), $"Combination of {nameof(startAddress)} and {nameof(count)} exceeds the addressation limit of {ushort.MaxValue}");
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string request = $":{unitId:X2}{(byte)ModbusFunctionCode.ReadHoldingRegisters:X2}";
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// Starting address
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byte[] addrBytes = startAddress.ToBigEndianBytes();
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request += $"{addrBytes[0]:X2}{addrBytes[1]:X2}";
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// Quantity
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byte[] countBytes = count.ToBigEndianBytes();
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request += $"{countBytes[0]:X2}{countBytes[1]:X2}";
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// LRC
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string lrc = LRC(request);
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request += lrc;
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// CRLF
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request += "\r\n";
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return Encoding.ASCII.GetBytes(request);
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}
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/// <inheritdoc/>
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public IReadOnlyList<HoldingRegister> DeserializeReadHoldingRegisters(IReadOnlyList<byte> response)
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{
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string responseMessage = Encoding.ASCII.GetString([.. response]).ToUpper();
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byte numBytes = HexToByte(responseMessage.Substring(5, 2));
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byte[] responsePayloadBytes = HexStringToByteArray(responseMessage.Substring(7, responseMessage.Length - 11));
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if (numBytes != responsePayloadBytes.Length)
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throw new ModbusException("Holding register byte count does not match.");
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int count = numBytes / 2;
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var holdingRegisters = new List<HoldingRegister>();
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for (int i = 0; i < count; i++)
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{
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holdingRegisters.Add(new HoldingRegister
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{
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Address = (ushort)i,
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HighByte = responsePayloadBytes[i * 2],
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LowByte = responsePayloadBytes[i * 2 + 1]
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});
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}
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return holdingRegisters;
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}
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/// <inheritdoc/>
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public IReadOnlyList<byte> SerializeReadInputRegisters(byte unitId, ushort startAddress, ushort count)
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{
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if (count < MIN_READ_COUNT || MAX_REGISTER_READ_COUNT < count)
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throw new ArgumentOutOfRangeException(nameof(count));
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if (ushort.MaxValue < (startAddress + count - 1))
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throw new ArgumentOutOfRangeException(nameof(count), $"Combination of {nameof(startAddress)} and {nameof(count)} exceeds the addressation limit of {ushort.MaxValue}");
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string request = $":{unitId:X2}{(byte)ModbusFunctionCode.ReadInputRegisters:X2}";
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// Starting address
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byte[] addrBytes = startAddress.ToBigEndianBytes();
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request += $"{addrBytes[0]:X2}{addrBytes[1]:X2}";
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// Quantity
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byte[] countBytes = count.ToBigEndianBytes();
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request += $"{countBytes[0]:X2}{countBytes[1]:X2}";
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// LRC
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string lrc = LRC(request);
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request += lrc;
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// CRLF
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request += "\r\n";
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return Encoding.ASCII.GetBytes(request);
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}
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/// <inheritdoc/>
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public IReadOnlyList<InputRegister> DeserializeReadInputRegisters(IReadOnlyList<byte> response)
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{
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string responseMessage = Encoding.ASCII.GetString([.. response]).ToUpper();
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byte numBytes = HexToByte(responseMessage.Substring(5, 2));
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byte[] responsePayloadBytes = HexStringToByteArray(responseMessage.Substring(7, responseMessage.Length - 11));
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if (numBytes != responsePayloadBytes.Length)
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throw new ModbusException("Input register byte count does not match.");
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int count = numBytes / 2;
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var inputRegisters = new List<InputRegister>();
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for (int i = 0; i < count; i++)
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{
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inputRegisters.Add(new InputRegister
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{
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Address = (ushort)i,
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HighByte = responsePayloadBytes[i * 2],
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LowByte = responsePayloadBytes[i * 2 + 1]
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});
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}
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return inputRegisters;
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}
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/// <inheritdoc/>
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public IReadOnlyList<byte> SerializeReadDeviceIdentification(byte unitId, ModbusDeviceIdentificationCategory category, ModbusDeviceIdentificationObject objectId)
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{
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if (!Enum.IsDefined(typeof(ModbusDeviceIdentificationCategory), category))
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throw new ArgumentOutOfRangeException(nameof(category));
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// Unit Id, Function code and Modbus Encapsulated Interface: Read Device Identification (MEI Type)
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string request = $":{unitId:X2}{(byte)ModbusFunctionCode.EncapsulatedInterface:X2}0E";
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// The category type (basic, regular, extended, individual)
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request += $"{(byte)category:X2}{(byte)objectId:X2}";
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// LRC
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string lrc = LRC(request);
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request += lrc;
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// CRLF
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request += "\r\n";
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return Encoding.ASCII.GetBytes(request);
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}
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/// <inheritdoc/>
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public DeviceIdentificationRaw DeserializeReadDeviceIdentification(IReadOnlyList<byte> response)
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{
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string responseMessage = Encoding.ASCII.GetString([.. response]).ToUpper();
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if (responseMessage.Substring(5, 2) != "0E")
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throw new ModbusException("The MEI type does not match");
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byte category = HexToByte(responseMessage.Substring(7, 2));
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if (!Enum.IsDefined(typeof(ModbusDeviceIdentificationCategory), category))
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throw new ModbusException("The category type does not match");
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var deviceIdentification = new DeviceIdentificationRaw
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{
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AllowsIndividualAccess = (HexToByte(responseMessage.Substring(9, 2)) & 0x80) == 0x80,
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MoreRequestsNeeded = responseMessage.Substring(11, 2) == "FF",
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NextObjectIdToRequest = HexToByte(responseMessage.Substring(13, 2)),
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};
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byte[] responsePayloadBytes = HexStringToByteArray(responseMessage.Substring(15, responseMessage.Length - 19));
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int baseOffset = 1; // Skip number of objects
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while (baseOffset < responsePayloadBytes.Length)
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{
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byte objectId = responsePayloadBytes[baseOffset];
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byte length = responsePayloadBytes[baseOffset + 1];
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byte[] data = responsePayloadBytes.Skip(baseOffset + 2).Take(length).ToArray();
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deviceIdentification.Objects.Add(objectId, data);
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baseOffset += 2 + length;
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}
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return deviceIdentification;
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}
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#endregion Read
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#region Write
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/// <inheritdoc/>
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public IReadOnlyList<byte> SerializeWriteSingleCoil(byte unitId, Coil coil)
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{
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#if NET8_0_OR_GREATER
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ArgumentNullException.ThrowIfNull(coil);
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#else
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if (coil == null)
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throw new ArgumentNullException(nameof(coil));
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#endif
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// Unit Id and Function code
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string request = $":{unitId:X2}{(byte)ModbusFunctionCode.WriteSingleCoil:X2}";
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// Starting address
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byte[] addrBytes = coil.Address.ToBigEndianBytes();
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request += $"{addrBytes[0]:X2}{addrBytes[1]:X2}";
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// Value
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request += $"{coil.HighByte:X2}{coil.LowByte:X2}";
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// LRC
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string lrc = LRC(request);
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request += lrc;
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// CRLF
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request += "\r\n";
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return Encoding.ASCII.GetBytes(request);
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}
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/// <inheritdoc/>
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public Coil DeserializeWriteSingleCoil(IReadOnlyList<byte> response)
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{
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string responseMessage = Encoding.ASCII.GetString([.. response]).ToUpper();
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return new Coil
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{
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Address = HexStringToByteArray(responseMessage.Substring(5, 4)).GetBigEndianUInt16(),
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HighByte = HexToByte(responseMessage.Substring(9, 2)),
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LowByte = HexToByte(responseMessage.Substring(11, 2))
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};
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}
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/// <inheritdoc/>
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public IReadOnlyList<byte> SerializeWriteSingleHoldingRegister(byte unitId, HoldingRegister register)
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{
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#if NET8_0_OR_GREATER
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ArgumentNullException.ThrowIfNull(register);
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#else
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if (register == null)
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throw new ArgumentNullException(nameof(register));
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#endif
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// Unit Id and Function code
|
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string request = $":{unitId:X2}{(byte)ModbusFunctionCode.WriteSingleRegister:X2}";
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// Starting address
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byte[] addrBytes = register.Address.ToBigEndianBytes();
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request += $"{addrBytes[0]:X2}{addrBytes[1]:X2}";
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// Value
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request += $"{register.HighByte:X2}{register.LowByte:X2}";
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// LRC
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string lrc = LRC(request);
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request += lrc;
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// CRLF
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request += "\r\n";
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return Encoding.ASCII.GetBytes(request);
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}
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/// <inheritdoc/>
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public HoldingRegister DeserializeWriteSingleHoldingRegister(IReadOnlyList<byte> response)
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{
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string responseMessage = Encoding.ASCII.GetString([.. response]).ToUpper();
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||||
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return new HoldingRegister
|
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{
|
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Address = HexStringToByteArray(responseMessage.Substring(5, 4)).GetBigEndianUInt16(),
|
||||
HighByte = HexToByte(responseMessage.Substring(9, 2)),
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LowByte = HexToByte(responseMessage.Substring(11, 2))
|
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};
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}
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/// <inheritdoc/>
|
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public IReadOnlyList<byte> SerializeWriteMultipleCoils(byte unitId, IReadOnlyList<Coil> coils)
|
||||
{
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||||
#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[] data = new byte[byteCount];
|
||||
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);
|
||||
data[bytePosition] |= bitMask;
|
||||
}
|
||||
}
|
||||
|
||||
// Unit Id and Function code
|
||||
string request = $":{unitId:X2}{(byte)ModbusFunctionCode.WriteMultipleCoils:X2}";
|
||||
|
||||
// Starting address
|
||||
byte[] addrBytes = firstAddress.ToBigEndianBytes();
|
||||
request += $"{addrBytes[0]:X2}{addrBytes[1]:X2}";
|
||||
|
||||
// Quantity
|
||||
byte[] countBytes = ((ushort)orderedList.Count).ToBigEndianBytes();
|
||||
request += $"{countBytes[0]:X2}{countBytes[1]:X2}";
|
||||
|
||||
// Byte count
|
||||
request += $"{byteCount:X2}";
|
||||
|
||||
// Data
|
||||
request += string.Join("", data.Select(b => $"{b:X2}"));
|
||||
|
||||
// LRC
|
||||
string lrc = LRC(request);
|
||||
request += lrc;
|
||||
|
||||
// CRLF
|
||||
request += "\r\n";
|
||||
|
||||
return Encoding.ASCII.GetBytes(request);
|
||||
}
|
||||
|
||||
/// <inheritdoc/>
|
||||
public (ushort FirstAddress, ushort NumberOfCoils) DeserializeWriteMultipleCoils(IReadOnlyList<byte> response)
|
||||
{
|
||||
string responseMessage = Encoding.ASCII.GetString([.. response]).ToUpper();
|
||||
|
||||
ushort firstAddress = HexStringToByteArray(responseMessage.Substring(5, 4)).GetBigEndianUInt16();
|
||||
ushort numberOfCoils = HexStringToByteArray(responseMessage.Substring(9, 4)).GetBigEndianUInt16();
|
||||
|
||||
return (firstAddress, numberOfCoils);
|
||||
}
|
||||
|
||||
/// <inheritdoc/>
|
||||
public IReadOnlyList<byte> SerializeWriteMultipleHoldingRegisters(byte unitId, IReadOnlyList<HoldingRegister> 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[] data = new byte[byteCount];
|
||||
for (int i = 0; i < orderedList.Count; i++)
|
||||
{
|
||||
data[2 * i] = orderedList[i].HighByte;
|
||||
data[2 * i + 1] = orderedList[i].LowByte;
|
||||
}
|
||||
|
||||
// Unit Id and Function code
|
||||
string request = $":{unitId:X2}{(byte)ModbusFunctionCode.WriteMultipleRegisters:X2}";
|
||||
|
||||
// Starting address
|
||||
byte[] addrBytes = firstAddress.ToBigEndianBytes();
|
||||
request += $"{addrBytes[0]:X2}{addrBytes[1]:X2}";
|
||||
|
||||
// Quantity
|
||||
byte[] countBytes = ((ushort)orderedList.Count).ToBigEndianBytes();
|
||||
request += $"{countBytes[0]:X2}{countBytes[1]:X2}";
|
||||
|
||||
// Byte count
|
||||
request += $"{byteCount:X2}";
|
||||
|
||||
// Data
|
||||
request += string.Join("", data.Select(b => $"{b:X2}"));
|
||||
|
||||
// LRC
|
||||
string lrc = LRC(request);
|
||||
request += lrc;
|
||||
|
||||
// CRLF
|
||||
request += "\r\n";
|
||||
|
||||
return Encoding.ASCII.GetBytes(request);
|
||||
}
|
||||
|
||||
/// <inheritdoc/>
|
||||
public (ushort FirstAddress, ushort NumberOfRegisters) DeserializeWriteMultipleHoldingRegisters(IReadOnlyList<byte> response)
|
||||
{
|
||||
string responseMessage = Encoding.ASCII.GetString([.. response]).ToUpper();
|
||||
|
||||
ushort firstAddress = HexStringToByteArray(responseMessage.Substring(5, 4)).GetBigEndianUInt16();
|
||||
ushort numberOfRegisters = HexStringToByteArray(responseMessage.Substring(9, 4)).GetBigEndianUInt16();
|
||||
|
||||
return (firstAddress, numberOfRegisters);
|
||||
}
|
||||
|
||||
#endregion Write
|
||||
|
||||
#region Validation
|
||||
|
||||
/// <inheritdoc/>
|
||||
public bool CheckResponseComplete(IReadOnlyList<byte> responseBytes)
|
||||
{
|
||||
if (responseBytes.Count < 3)
|
||||
return false;
|
||||
|
||||
for (int i = responseBytes.Count - 2; i >= 0; i--)
|
||||
{
|
||||
// ASCII terminates with CR LF (\r\n)
|
||||
if (responseBytes[i] == 0x0D && responseBytes[i + 1] == 0x0A)
|
||||
return true;
|
||||
}
|
||||
|
||||
return false;
|
||||
}
|
||||
|
||||
/// <inheritdoc/>
|
||||
public void ValidateResponse(IReadOnlyList<byte> request, IReadOnlyList<byte> response)
|
||||
{
|
||||
string requestMessage = Encoding.ASCII.GetString([.. request]).ToUpper();
|
||||
string responseMessage = Encoding.ASCII.GetString([.. response]).ToUpper();
|
||||
|
||||
// Check header
|
||||
if (!responseMessage.StartsWith(":"))
|
||||
throw new ModbusException("The protocol header is missing.");
|
||||
|
||||
// Check trailer
|
||||
if (!responseMessage.EndsWith("\r\n"))
|
||||
throw new ModbusException("The protocol tail is missing.");
|
||||
|
||||
string calculatedLrc = LRC(responseMessage, 1, responseMessage.Length - 5);
|
||||
string receivedLrc = responseMessage.Substring(responseMessage.Length - 4, 2);
|
||||
if (calculatedLrc != receivedLrc)
|
||||
throw new ModbusException("LRC check failed.");
|
||||
|
||||
if (requestMessage.Substring(1, 2) != responseMessage.Substring(1, 2))
|
||||
throw new ModbusException("Unit Identifier does not match.");
|
||||
|
||||
byte fnCode = HexToByte(responseMessage.Substring(3, 2));
|
||||
bool isError = (fnCode & 0x80) == 0x80;
|
||||
if (isError)
|
||||
fnCode = (byte)(fnCode ^ 0x80); // === fnCode & 0x7F
|
||||
|
||||
if (requestMessage.Substring(3, 2) != fnCode.ToString("X2"))
|
||||
throw new ModbusException("Function code does not match.");
|
||||
|
||||
if (isError)
|
||||
throw new ModbusException("Remote Error") { ErrorCode = (ModbusErrorCode)HexToByte(responseMessage.Substring(5, 2)) };
|
||||
|
||||
if (new[] { 0x01, 0x02, 0x03, 0x04 }.Contains(fnCode))
|
||||
{
|
||||
// : ID FN NU DA XX \r\n
|
||||
byte charByteCount = HexToByte(responseMessage.Substring(5, 2));
|
||||
if (responseMessage.Length != charByteCount * 2 + 11)
|
||||
throw new ModbusException("Number of following bytes does not match.");
|
||||
}
|
||||
|
||||
if (new[] { 0x05, 0x06, 0x0F, 0x10 }.Contains(fnCode))
|
||||
{
|
||||
// : ID FN 00 10 00 30 XX \r\n
|
||||
if (responseMessage.Length != 17)
|
||||
throw new ModbusException("Number of bytes does not match.");
|
||||
}
|
||||
|
||||
// TODO: Do we want to check 0x2B too?
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Calculate LRC for Modbus ASCII.
|
||||
/// </summary>
|
||||
/// <param name="message">The message chars.</param>
|
||||
/// <param name="start">The start index.</param>
|
||||
/// <param name="length">The number of bytes to calculate.</param>
|
||||
public static string LRC(string message, int start = 1, int? length = null)
|
||||
{
|
||||
if (string.IsNullOrWhiteSpace(message))
|
||||
throw new ArgumentNullException(nameof(message));
|
||||
|
||||
if (start < 0 || start >= message.Length)
|
||||
throw new ArgumentOutOfRangeException(nameof(start));
|
||||
|
||||
length ??= message.Length - start;
|
||||
|
||||
if (length <= 0 || start + length > message.Length)
|
||||
throw new ArgumentOutOfRangeException(nameof(length));
|
||||
|
||||
if (length % 2 != 0)
|
||||
throw new ArgumentException("The number of chars to calculate the LRC must be even.", nameof(length));
|
||||
|
||||
string subStr = message.Substring(start, length.Value);
|
||||
|
||||
// Step 1:
|
||||
// Add all bytes in the message, excluding the starting 'colon' and ending CRLF.
|
||||
// Add them into an 8–bit field, so that carries will be discarded.
|
||||
byte lrc = 0x00;
|
||||
foreach (byte b in HexStringToByteArray(subStr))
|
||||
lrc += b;
|
||||
|
||||
// Step 2:
|
||||
// Subtract the final field value from FF hex (all 1's), to produce the ones-complement.
|
||||
byte oneComplement = (byte)(lrc ^ 0xFF);
|
||||
|
||||
// Step 3:
|
||||
// Add 1 to produce the twos-complement.
|
||||
return ((byte)(oneComplement + 0x01)).ToString("X2");
|
||||
}
|
||||
|
||||
#endregion Validation
|
||||
|
||||
#region Private Helper
|
||||
|
||||
private static byte[] HexStringToByteArray(string hexString)
|
||||
{
|
||||
return Enumerable
|
||||
.Range(0, hexString.Length)
|
||||
.Where(x => x % 2 == 0)
|
||||
.Select(x => HexToByte(hexString.Substring(x, 2)))
|
||||
.ToArray();
|
||||
}
|
||||
|
||||
private static byte HexToByte(string hex)
|
||||
=> Convert.ToByte(hex, 16);
|
||||
|
||||
#endregion Private Helper
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user