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我剛剛在使用此Modbus TCP庫（https://github.com/stephanstricker/modbusTCP/tree/master/ModbusTCP/ModbusTCP）和本文檔以獲得對函數20（http://www.modbus.org/docs/Modbus_Application_Protocol_V1_1b3.pdf）的參考。問題是它不支持功能代碼20（讀取通用參考/文件）。現在我只是想創建自己的功能，可以處理它，但是我得到的迴應是10兩個字節數組和1如何使用C＃實現Modbus功能20？
這裏是請求頭，我嘗試使用：
private byte[] CreateReadFileHeader(ushort id, byte unit, byte count, ushort fileNumber, ushort recordNumber, ushort recordLength)
{
byte[] data = new byte[13];
byte[] _id = BitConverter.GetBytes((short)id);
data[0] = _id[1]; // Transaction ID high byte
data[1] = _id[0]; // Transaction ID low byte
data[2] = 11; // Packet Length
data[3] = unit; // Slave address
data[4] = fctReadFile; // Function code = 20
//byte[] _adr = BitConverter.GetBytes((short)IPAddress.HostToNetworkOrder((short)startAddress));
data[5] = 7; // Byte Count 0x07 to 0xF5 bytes
data[6] = 6; // Reference Type
byte[] _FileNum = BitConverter.GetBytes((short)IPAddress.HostToNetworkOrder((short)fileNumber));
data[7] = 0; // File Number Hi
data[8] = 1; // File Number Lo
byte[] _RecordNum = BitConverter.GetBytes((short)IPAddress.HostToNetworkOrder(10000));
data[9] = _RecordNum[0]; // Record Number Hi
data[10] = _RecordNum[1]; // Record Number Lo
byte[] _RecordLength = BitConverter.GetBytes((short)IPAddress.HostToNetworkOrder((short)recordLength));
data[11] = 0; // Record Length Hi
data[12] = 6; // Record Length Lo
return data;
}
這裏是調用請求的代碼：
private byte[] WriteSyncData(byte[] write_data, ushort id)
{
if (tcpSynCl.Connected)
{
try
{
tcpSynCl.Send(write_data, 0, write_data.Length, SocketFlags.None);
int result = tcpSynCl.Receive(tcpSynClBuffer, 0, tcpSynClBuffer.Length, SocketFlags.None);
byte unit = tcpSynClBuffer[6];
byte function = tcpSynClBuffer[7];
byte[] data;
if (result == 0) CallException(id, unit, write_data[7], excExceptionConnectionLost);
// ------------------------------------------------------------
// Response data is slave exception
if (function > excExceptionOffset)
{
function -= excExceptionOffset;
CallException(id, unit, function, tcpSynClBuffer[8]);
return null;
}
// ------------------------------------------------------------
// Write response data
else if ((function >= fctWriteSingleCoil) && (function != fctReadWriteMultipleRegister)&&(function!=fctReadFile))
{
data = new byte[2];
Array.Copy(tcpSynClBuffer, 10, data, 0, 2);
}
// ------------------------------------------------------------
// Read response data
else
{
data = new byte[tcpSynClBuffer[8]];
Array.Copy(tcpSynClBuffer, 9, data, 0, tcpSynClBuffer[8]);
}
return data;
}
catch (SystemException)
{
CallException(id, write_data[6], write_data[7], excExceptionConnectionLost);
}
}
else CallException(id, write_data[6], write_data[7], excExceptionConnectionLost);
return null;
}
的TCP同步緩衝返回[0,0,11,1,0,3,6,128,1,0,10,1,0， 0,0，...]
更新：
我修改了我的請求標題。
private byte[] CreateReadFileHeader(ushort id, byte unit, byte count, ushort fileNumber, ushort recordNumber, ushort recordLength)
{
byte[] data = new byte[17];
byte[] _id = BitConverter.GetBytes((short)id);
data[0] = 0;//_id[1]; // Transaction ID high byte
data[1] = 0;//_id[0]; // Transaction ID low byte
byte[] _size = BitConverter.GetBytes((short)IPAddress.HostToNetworkOrder((short)(11)));
data[2] = 0; //Protocol identifier
data[3] = 0; //Protocol identifier
data[4] = 0; // Packet Length
data[5] = 11; // Packet Length
data[6] = unit; //Unit Identifier
data[7] = fctReadFile; // Function code
//byte[] _adr = BitConverter.GetBytes((short)IPAddress.HostToNetworkOrder((short)startAddress));
data[8] = 0; // Byte Count 0x07 to 0xF5 bytes
data[9] = 7; // Byte Count 0x07 to 0xF5 bytes
data[10] = 6; // Reference Type
byte[] _FileNum = BitConverter.GetBytes((short)IPAddress.HostToNetworkOrder((short)fileNumber));
data[11] = 0; // File Number Hi
data[12] = 1; // File Number Lo
byte[] _RecordNum = BitConverter.GetBytes((short)IPAddress.HostToNetworkOrder(10000));
data[13] = _RecordNum[0]; // Record Number Hi
data[14] = _RecordNum[1]; // Record Number Lo
byte[] _RecordLength = BitConverter.GetBytes((short)IPAddress.HostToNetworkOrder((short)recordLength));
data[15] =0; // Record Length Hi
data[16] =1; // Record Length Lo
return data;
}
//I use this function to call the request
public void ReadFile(ushort id, byte unit, ref byte[] values)
{
byte[] write_data = CreateReadFileHeader(id, unit, 7, 1, 10000, 6);
tcpSynCl.Send(write_data, 0, write_data.Length, SocketFlags.None);
int result = tcpSynCl.Receive(tcpSynClBuffer, 0, tcpSynClBuffer.Length, SocketFlags.None);
values = tcpSynClBuffer;
}
，現在返回：
[0,0,0,0,0,5,1,20,4,0,0,0，..]