[Modbus] 如何 用 C# 開發 Modbus Master Protocol - (08) 實作 RtuModbusRequest
續上篇，Modbus TCP Protocol 暫時告一段落，緊接著往 Modbus RTU Protocol 邁進
要特別注意的是，Modbus RUT 必須要檢查 CRC，CRC 的元件在這裡我是引用 Tako.CRC.dll
https://tako.codeplex.com/downloads/get/663904
下圖為 RTU 框架，要特別注意 CRC 的擺放位置，是先擺 Low Byte 再擺 Hi Byte
依 Modbus RTU 實作 Request Protocol
{
private byte[] createReadMessage(byte Unit, EnumModbusFunctionCode FunctionCode, ushort StartAddress, ushort Quantity)
{
using (MemoryStream memory = new MemoryStream())
{
memory.WriteByte((byte)Unit);
memory.WriteByte((byte)FunctionCode);
memory.WriteByte((byte)(StartAddress >> 8));
memory.WriteByte((byte)(StartAddress));
memory.WriteByte((byte)(Quantity >> 8));
memory.WriteByte((byte)(Quantity));
var crcArray = ModbusUtility.CalculateCRC(memory.ToArray());
memory.Write(crcArray, 0, crcArray.Length);
return memory.ToArray();
}
}
public override byte[] ReadCoils(byte Unit, ushort StartAddress, ushort Quantity)
{
this.QuantityValidate(StartAddress, Quantity, 1, 2000);
var requestArray = this.createReadMessage(Unit, EnumModbusFunctionCode.ReadCoils, StartAddress, Quantity);
return requestArray;
}
public override byte[] ReadDiscreteInputs(byte Unit, ushort StartAddress, ushort Quantity)
{
this.QuantityValidate(StartAddress, Quantity, 1, 2000);
var requestArray = this.createReadMessage(Unit, EnumModbusFunctionCode.ReadDiscreteInputs, StartAddress, Quantity);
return requestArray;
}
public override byte[] ReadHoldingRegisters(byte Unit, ushort StartAddress, ushort Quantity)
{
this.QuantityValidate(StartAddress, Quantity, 1, 175);
var requestArray = this.createReadMessage(Unit, EnumModbusFunctionCode.ReadHoldingRegisters, StartAddress, Quantity);
return requestArray;
}
public override byte[] ReadInputRegisters(byte Unit, ushort StartAddress, ushort Quantity)
{
this.QuantityValidate(StartAddress, Quantity, 1, 175);
var requestArray = this.createReadMessage(Unit, EnumModbusFunctionCode.ReadInputRegisters, StartAddress, Quantity);
return requestArray;
}
public override byte[] WriteSingleCoil(byte Unit, ushort OutputAddress, bool OutputValue)
{
ushort outputValue = 0x0000;
if (OutputValue)
{
outputValue = 0xFF00;
}
using (MemoryStream memory = new MemoryStream())
{
memory.WriteByte((byte)Unit);
memory.WriteByte((byte)EnumModbusFunctionCode.WriteSingleCoil);
memory.WriteByte((byte)(OutputAddress >> 8));
memory.WriteByte((byte)(OutputAddress));
memory.WriteByte((byte)(outputValue >> 8));
memory.WriteByte((byte)(outputValue));
var crcArray = ModbusUtility.CalculateCRC(memory.ToArray());
memory.Write(crcArray, 0, crcArray.Length);
return memory.ToArray();
}
}
public override byte[] WriteSingleRegister(byte Unit, ushort OutputAddress, short OutputValue)
{
using (MemoryStream memory = new MemoryStream())
{
memory.WriteByte((byte)Unit);
memory.WriteByte((byte)EnumModbusFunctionCode.WriteSingleRegister);
memory.WriteByte((byte)(OutputAddress >> 8));
memory.WriteByte((byte)(OutputAddress));
memory.WriteByte((byte)(OutputValue >> 8));
memory.WriteByte((byte)(OutputValue));
var crcArray = ModbusUtility.CalculateCRC(memory.ToArray());
memory.Write(crcArray, 0, crcArray.Length);
return memory.ToArray();
}
}
public override byte[] WriteMultipleCoils(byte Unit, ushort StartAddress, ushort Quantity, byte[] OutputValues)
{
this.QuantityValidate(StartAddress, Quantity, 1, 0x07B0);
byte counter = base.GetByteCount(Quantity);
using (MemoryStream memory = new MemoryStream())
{
memory.WriteByte((byte)Unit);
memory.WriteByte((byte)EnumModbusFunctionCode.WriteMultipleCoils);
memory.WriteByte((byte)(StartAddress >> 8));
memory.WriteByte((byte)(StartAddress));
memory.WriteByte((byte)(Quantity >> 8));
memory.WriteByte((byte)(Quantity));
memory.WriteByte((byte)(counter));
memory.Write(OutputValues, 0, OutputValues.Length);
var crcArray = ModbusUtility.CalculateCRC(memory.ToArray());
memory.Write(crcArray, 0, crcArray.Length);
return memory.ToArray();
}
}
public override byte[] WriteMultipleRegisters(byte Unit, ushort StartAddress, ushort Quantity, short[] OutputValues)
{
this.QuantityValidate(StartAddress, Quantity, 1, 0x007B);
byte[] outputArray = base.GetByteCount(OutputValues);
byte counter = (byte)outputArray.Length;
if (Quantity * 2 != outputArray.Length)
{
ModbusException.GetModbusException(0x02);
}
using (MemoryStream memory = new MemoryStream())
{
memory.WriteByte((byte)Unit);
memory.WriteByte((byte)EnumModbusFunctionCode.WriteMultipleRegisters);
memory.WriteByte((byte)(StartAddress >> 8));
memory.WriteByte((byte)(StartAddress));
memory.WriteByte((byte)(Quantity >> 8));
memory.WriteByte((byte)(Quantity));
memory.WriteByte((byte)(counter));
memory.Write(outputArray, 0, outputArray.Length);
var crcArray = ModbusUtility.CalculateCRC(memory.ToArray());
memory.Write(crcArray, 0, crcArray.Length);
return memory.ToArray();
}
}
}
ModbusUtility.CalculateCRC 方法取得CRC
{
private CRCManager m_CrcManager = new CRCManager();
private AbsCRCProvider m_CrcProvider;
public byte[] CalculateCRC(byte[] DataArray)
{
if (m_CrcProvider == null)
{
m_CrcProvider = m_CrcManager.CreateCRCProvider(EnumCRCProvider.CRC16Modbus);
}
var crcArray = m_CrcProvider.GetCRC(DataArray).CrcArray;
Array.Reverse(crcArray);
return crcArray;
}
}
建立單元測試，驗證資料組合的正確性
[TestMethod()]
public void ReadCoilsTest()
{
RtuModbusRequest target = new RtuModbusRequest();
byte Unit = 1;
ushort StartAddress = 0;
ushort Quantity = 10;
byte[] expected = _modbusUtility.HexStringToBytes("01 01 00 00 00 0A BC 0D");
byte[] actual;
actual = target.ReadCoils(Unit, StartAddress, Quantity);
Assert.IsTrue(expected.SequenceEqual(actual));
}
[TestMethod()]
public void ReadDiscreteInputsTest()
{
RtuModbusRequest target = new RtuModbusRequest();
byte Unit = 1;
ushort StartAddress = 0;
ushort Quantity = 10;
byte[] expected = _modbusUtility.HexStringToBytes("01 02 00 00 00 0A F8 0D");
byte[] actual;
actual = target.ReadDiscreteInputs(Unit, StartAddress, Quantity);
Assert.IsTrue(expected.SequenceEqual(actual));
}
[TestMethod()]
public void ReadHoldingRegistersTest()
{
RtuModbusRequest target = new RtuModbusRequest();
byte Unit = 1;
ushort StartAddress = 0;
ushort Quantity = 10;
byte[] expected = _modbusUtility.HexStringToBytes("01 03 00 00 00 0A C5 CD");
byte[] actual;
actual = target.ReadHoldingRegisters(Unit, StartAddress, Quantity);
Assert.IsTrue(expected.SequenceEqual(actual));
}
[TestMethod()]
public void ReadInputRegistersTest()
{
RtuModbusRequest target = new RtuModbusRequest();
byte Unit = 1;
ushort StartAddress = 0;
ushort Quantity = 10;
byte[] expected = _modbusUtility.HexStringToBytes("01 04 00 00 00 0A 70 0D");
byte[] actual;
actual = target.ReadInputRegisters(Unit, StartAddress, Quantity);
Assert.IsTrue(expected.SequenceEqual(actual));
}
[TestMethod()]
public void WriteSingleCoilTest()
{
RtuModbusRequest target = new RtuModbusRequest();
byte Unit = 1;
ushort StartAddress = 2;
bool OutputValue = true;
byte[] expected = _modbusUtility.HexStringToBytes("01 05 00 02 FF 00 2D FA");
byte[] actual;
actual = target.WriteSingleCoil(Unit, StartAddress, OutputValue);
Assert.IsTrue(expected.SequenceEqual(actual));
}
[TestMethod()]
public void WriteSingleRegisterTest()
{
RtuModbusRequest target = new RtuModbusRequest();
byte Unit = 1;
ushort OutputAddress = 2;
short OutputValue = 2344;
byte[] expected = _modbusUtility.HexStringToBytes("01 06 00 02 09 28 2E 44");
byte[] actual;
actual = target.WriteSingleRegister(Unit, OutputAddress, OutputValue);
Assert.IsTrue(expected.SequenceEqual(actual));
}
[TestMethod()]
public void WriteMultipleCoilsTest()
{
RtuModbusRequest target = new RtuModbusRequest();
byte Unit = 1;
ushort StartAddress = 0;
ushort Quantity = 24;
byte[] OutputValues = new byte[] { 147, 82, 5 };
byte[] expected = _modbusUtility.HexStringToBytes("01 0F 00 00 00 18 03 93 52 05 4D 3A");
byte[] actual;
actual = target.WriteMultipleCoils(Unit, StartAddress, Quantity, OutputValues);
Assert.IsTrue(expected.SequenceEqual(actual));
}
[TestMethod()]
public void WriteMultipleRegistersTest()
{
RtuModbusRequest target = new RtuModbusRequest();
byte Unit = 1;
ushort StartAddress = 0;
ushort Quantity = 10;
short[] OutputValues = new short[] { 1234, 0, 0, -13, 12, -86, 223, 0, 0, -8 };
byte[] expected = _modbusUtility.HexStringToBytes("01 10 00 00 00 0A 14 04 D2 00 00 00 00 FF F3 00 0C FF AA 00 DF 00 00 00 00 FF F8 58 66");
byte[] actual;
actual = target.WriteMultipleRegisters(Unit, StartAddress, Quantity, OutputValues);
Assert.IsTrue(expected.SequenceEqual(actual));
}
若有謬誤，煩請告知，新手發帖請多包涵
Microsoft MVP Award 2010~2017 C# 第四季
Microsoft MVP Award 2018~2022 .NET
