/// <summary>
/// Performs a request in the ASCII mode.
/// </summary>
protected bool AsciiRequest(DataUnit dataUnit)
{
bool result = false;
// send request
log.WriteLine(dataUnit.ReqDescr);
Connection.WriteLine(dataUnit.ReqStr, out string logText);
log.WriteLine(logText);
// receive response
string line = Connection.ReadLine(Timeout, out logText);
log.WriteLine(logText);
int lineLen = line == null ? 0 : line.Length;
if (lineLen >= 3)
{
int aduLen = (lineLen - 1) / 2;
if (aduLen == dataUnit.RespAduLen && lineLen % 2 == 1)
{
// receive response ADU
byte[] aduBuf = new byte[aduLen];
bool parseOK = true;
for (int i = 0, j = 1; i < aduLen && parseOK; i++, j += 2)
{
try
{
aduBuf[i] = byte.Parse(line.Substring(j, 2), NumberStyles.HexNumber);
}
catch
{
log.WriteLine(ModbusPhrases.IncorrectSymbol);
parseOK = false;
}
}
if (parseOK)
{
if (aduBuf[aduLen - 1] == ModbusUtils.LRC(aduBuf, 0, aduLen - 1))
{
// decode response
if (dataUnit.DecodeRespPDU(aduBuf, 1, aduLen - 2, out string errMsg))
{
log.WriteLine(ModbusPhrases.OK);
result = true;
}
else
{
log.WriteLine(errMsg + "!");
}
}
else
{
log.WriteLine(ModbusPhrases.LrcError);
}
}
}
else
{
log.WriteLine(ModbusPhrases.IncorrectAduLength);
}
}
else
{
log.WriteLine(ModbusPhrases.CommErrorWithExclamation);
}
return(result);
}
/// <summary>
/// Performs a request in the TCP mode.
/// </summary>
protected bool TcpRequest(DataUnit dataUnit)
{
bool result = false;
// specify transaction ID
if (++TransactionID == 0)
{
TransactionID = 1;
}
dataUnit.ReqADU[0] = (byte)(TransactionID / 256);
dataUnit.ReqADU[1] = (byte)(TransactionID % 256);
// send request
log.WriteLine(dataUnit.ReqDescr);
Connection.Write(dataUnit.ReqADU, 0, dataUnit.ReqADU.Length, ProtocolFormat.Hex, out string logText);
log.WriteLine(logText);
// receive response
// read MBAP header
int readCnt = Connection.Read(InBuf, 0, 7, Timeout, ProtocolFormat.Hex, out logText);
log.WriteLine(logText);
if (readCnt == 7)
{
int pduLen = InBuf[4] * 256 + InBuf[5] - 1;
if (InBuf[0] == dataUnit.ReqADU[0] && InBuf[1] == dataUnit.ReqADU[1] && // transaction ID
InBuf[2] == 0 && InBuf[3] == 0 && pduLen > 0 && // protocol ID
InBuf[6] == dataUnit.ReqADU[6]) // unit ID
{
// read PDU
readCnt = Connection.Read(InBuf, 7, pduLen, Timeout, ProtocolFormat.Hex, out logText);
log.WriteLine(logText);
if (readCnt == pduLen)
{
// decode response
if (dataUnit.DecodeRespPDU(InBuf, 7, pduLen, out string errMsg))
{
log.WriteLine(ModbusPhrases.OK);
result = true;
}
else
{
log.WriteLine(errMsg + "!");
}
}
else
{
log.WriteLine(ModbusPhrases.CommErrorWithExclamation);
}
}
else
{
log.WriteLine(ModbusPhrases.IncorrectMbap);
}
}
else
{
log.WriteLine(ModbusPhrases.CommErrorWithExclamation);
}
return(result);
}
/// <summary>
/// Performs a request in the PDU mode.
/// </summary>
protected bool RtuRequest(DataUnit dataUnit)
{
bool result = false;
// send request
log.WriteLine(dataUnit.ReqDescr);
Connection.Write(dataUnit.ReqADU, 0, dataUnit.ReqADU.Length, ProtocolFormat.Hex, out string logText);
log.WriteLine(logText);
// receive response
// partial read to calculate PDU length
const int FirstCount = 2;
int readCnt = Connection.Read(InBuf, 0, FirstCount, Timeout, ProtocolFormat.Hex, out logText);
log.WriteLine(logText);
if (readCnt != FirstCount)
{
log.WriteLine(ModbusPhrases.CommErrorWithExclamation);
}
else if (InBuf[0] != dataUnit.ReqADU[0]) // validate device address
{
log.WriteLine(ModbusPhrases.IncorrectDevAddr);
}
else if (!(InBuf[1] == dataUnit.FuncCode || InBuf[1] == dataUnit.ExcFuncCode)) // validate function code
{
log.WriteLine(ModbusPhrases.IncorrectPduFuncCode);
}
else
{
int pduLen;
int count;
if (InBuf[1] == dataUnit.FuncCode)
{
pduLen = dataUnit.RespPduLen;
count = dataUnit.RespAduLen - FirstCount;
}
else // exception received
{
pduLen = 2;
count = 3;
}
// read rest of response
readCnt = Connection.Read(InBuf, FirstCount, count, Timeout, ProtocolFormat.Hex, out logText);
log.WriteLine(logText);
if (readCnt != count)
{
log.WriteLine(ModbusPhrases.CommErrorWithExclamation);
}
else if (InBuf[pduLen + 1] + InBuf[pduLen + 2] * 256 != ModbusUtils.CRC16(InBuf, 0, pduLen + 1))
{
log.WriteLine(ModbusPhrases.CrcError);
}
else if (dataUnit.DecodeRespPDU(InBuf, 1, pduLen, out string errMsg))
{
log.WriteLine(ModbusPhrases.OK);
result = true;
}
else
{
log.WriteLine(errMsg + "!");
}
}
return(result);
}