// TODO: too many arguments
// Build common part of modbus request, decorate it with transport layer specific header, send request and get response PDU back
public byte[] SendModbusRequest(byte id, ModbusFunctionCodes functionCode, ushort readAddress, ushort readCount, ushort writeAddress, ushort writeCount, byte[] writeData)
{
// Build common part of modbus request
byte[] requestPdu = BuildRequestPdu(id, functionCode, readAddress, readCount, writeAddress, writeCount, writeData);
// Decorate common part of modbus request with transport layer specific header
byte[] requestAdu = BuildRequestAdu(requestPdu);
// Send modbus request and return response
return(Query(requestAdu)); // response PDU
}
public static ModbusTCPMessage ParseBytes(IEnumerable <byte> message)
{
var og = new ModbusTCPMessage(message);
ModbusFunctionCodes func = og.PDU.FunctionCode;
switch (func)
{
case ModbusFunctionCodes.ReadHoldingRegisters:
return(new ReadRegistersMessage(message));
case ModbusFunctionCodes.PresetMultipleRegisters:
return(new WriteHoldingRegistersMessage(message));
default:
return(new ModbusTCPMessage(message));
}
}
// TODO: Refactor this. Too many lines and arguments; ugly switch statement. Hard to follow. Break out a new class.
// Build common part of modbus request
private byte[] BuildRequestPdu(byte id, ModbusFunctionCodes functionCode, ushort readAddress, ushort readCount, ushort writeAddress, ushort writeCount, byte[] writeData)
{
byte[] help; // Used to convert ushort into bytes
byte[] requestPdu = null;
switch (functionCode)
{
case ModbusFunctionCodes.ReadCoils:
case ModbusFunctionCodes.ReadDiscreteInputs:
case ModbusFunctionCodes.ReadHoldingRegisters:
case ModbusFunctionCodes.ReadInputRegisters:
requestPdu = new byte[6];
// Build request header
requestPdu[0] = id;
requestPdu[1] = (byte)functionCode;
help = BitConverter.GetBytes(readAddress);
requestPdu[2] = help[1]; // Start read address -Hi
requestPdu[3] = help[0]; // Start read address -Lo
help = BitConverter.GetBytes(readCount);
requestPdu[4] = help[1]; // Number of coils or register to read -Hi
requestPdu[5] = help[0]; // Number of coils or register to read -Lo
break;
case ModbusFunctionCodes.WriteSingleCoil:
requestPdu = new byte[6];
// Build request header
requestPdu[0] = id;
requestPdu[1] = 0x05;
help = BitConverter.GetBytes(writeAddress);
requestPdu[2] = help[1]; // Address of coil to force -Hi
requestPdu[3] = help[0]; // Address of coil to force -Lo
// Copy data
requestPdu[4] = writeData[0]; // Output value -Hi ( 0xFF or 0x00 )
requestPdu[5] = 0x00; // Output value -Lo ( const: 0x00 )
break;
case ModbusFunctionCodes.WriteSingleRegister:
requestPdu = new byte[6];
// Build request header
requestPdu[0] = id;
requestPdu[1] = 0x06;
help = BitConverter.GetBytes(writeAddress);
requestPdu[2] = help[1]; // Address of register to force -Hi
requestPdu[3] = help[0]; // Address of register to force -Lo
requestPdu[4] = writeData[1]; // Output value -Hi
requestPdu[5] = writeData[0]; // Output value -Lo
break;
case ModbusFunctionCodes.GetCommEventCounter:
requestPdu = new byte[2];
// Build request header
requestPdu[0] = id;
requestPdu[1] = 0x0B;
break;
case ModbusFunctionCodes.WriteMultipleCoils:
byte byteCount = (byte)(writeCount / 8);
if ((writeCount % 8) > 0)
{
byteCount += 1;
}
requestPdu = new byte[7 + byteCount];
// Build request header
requestPdu[0] = id;
requestPdu[1] = 0x0F;
help = BitConverter.GetBytes(writeAddress);
requestPdu[2] = help[1]; // Start address of coils to force -Hi
requestPdu[3] = help[0]; // Start address of coils to force -Lo
help = BitConverter.GetBytes(writeCount);
requestPdu[4] = help[1]; // Number of coils to write -Hi
requestPdu[5] = help[0]; // Number of coils to write -Lo
requestPdu[6] = byteCount;
// Copy data
for (int i = 0; i < byteCount; ++i)
{
requestPdu[7 + i] = writeData[i];
}
break;
case ModbusFunctionCodes.WriteMultipleRegisters:
requestPdu = new byte[7 + (writeCount * 2)];
// Build request header
requestPdu[0] = id;
requestPdu[1] = 0x10;
help = BitConverter.GetBytes(writeAddress);
requestPdu[2] = help[1]; // Start address of coils to force -Hi
requestPdu[3] = help[0]; // Start address of coils to force -Lo
help = BitConverter.GetBytes(writeCount);
requestPdu[4] = help[1]; // Number of register to write -Hi
requestPdu[5] = help[0]; // Number of register to write -Lo
requestPdu[6] = (byte)(writeCount * 2); // Number of bytes to write
// Copy data
for (int i = 0; i < (writeCount * 2); i++)
{
requestPdu[7 + i] = writeData[i];
}
break;
case ModbusFunctionCodes.MaskWriteRegister:
requestPdu = new byte[8];
// Build request header
requestPdu[0] = id;
requestPdu[1] = 0x16;
help = BitConverter.GetBytes(writeAddress);
requestPdu[2] = help[1]; // Address of register to force -Hi
requestPdu[3] = help[0]; // Address of register to force -Lo
requestPdu[4] = writeData[1]; // And_Mask -Hi
requestPdu[5] = writeData[0]; // And_Mask -Lo
requestPdu[6] = writeData[3]; // Or_Mask -Hi
requestPdu[7] = writeData[2]; // Or_Mask -Lo
break;
case ModbusFunctionCodes.ReadWriteMultipleRegisters:
requestPdu = new byte[11 + (writeCount * 2)];
// Build request header
requestPdu[0] = id;
requestPdu[1] = 0x17;
help = BitConverter.GetBytes(readAddress);
requestPdu[2] = help[1]; // Start read address -Hi
requestPdu[3] = help[0]; // Start read address -Lo
help = BitConverter.GetBytes(readCount);
requestPdu[4] = help[1]; // Number of register to read -Hi
requestPdu[5] = help[0]; // Number of register to read -Lo
help = BitConverter.GetBytes(writeAddress);
requestPdu[6] = help[1]; // Start write address -Hi
requestPdu[7] = help[0]; // Start write address -Lo
help = BitConverter.GetBytes(writeCount);
requestPdu[8] = help[1]; // Number of register to write -Hi
requestPdu[9] = help[0]; // Number of register to write -Lo
requestPdu[10] = (byte)(writeCount * 2); // Number of bytes to write
// Copy data
for (int i = 0; i < (writeCount * 2); ++i)
{
requestPdu[11 + i] = writeData[i];
}
break;
} // switch
return(requestPdu);
}
public ProtocolDataUnit(ModbusFunctionCodes functionCode, IEnumerable <byte> data)
{
FunctionCode = functionCode;
Data = data;
}
