/// <summary>
/// Reads process data from the selected location and device resources.
/// </summary>
/// <param name="pBlock"><see cref="T:CAS.Lib.CommonBus.ApplicationLayer.IBlockDescription" /> selecting the resource containing the data block to be read.</param>
/// <param name="pStation">Address of the remote station connected to the common field bus. –1 if not applicable.</param>
/// <param name="pData">The buffer <see cref="T:CAS.Lib.CommonBus.ApplicationLayer.IReadValue" /> containing the requested data.</param>
/// <param name="pRetries">Number of retries to get data.</param>
/// <returns>Result of the operation</returns>
/// <exception cref="System.ArgumentOutOfRangeException"></exception>
public AL_ReadData_Result ReadData(IBlockDescription pBlock, int pStation, out IReadValue pData, byte pRetries)
{
pData = null;
if (pBlock.dataType != 0)
{
TraceSource.TraceMessage(TraceEventType.Error, 149, $"Wrong dataType: {pBlock.dataType}; only data type = 0 is expected");
m_statistic.IncStRxInvalid();
}
if (!Connected)
{
TraceSource.TraceMessage(TraceEventType.Verbose, 165, $"ReadData failed because it is not connected; retries/limit={m_RetryCount}/{this.m_TextReaderProtocolParameters.MaxNumberOfRetries}.");
return(AL_ReadData_Result.ALRes_DisInd);
}
m_statistic.IncStTxFrameCounter();
IDataEntity _copy = Interlocked.Exchange <IDataEntity>(ref m_Fifo, m_Fifo);
bool _retResult = _copy != null;
m_statistic.RxDataBlock(_retResult);
if (!_retResult)
{
m_statistic.IncStRxNoResponseCounter();
TraceSource.TraceMessage(TraceEventType.Information, 186, $"ReadData failed; retries/limit={m_RetryCount}/{this.m_TextReaderProtocolParameters.MaxNumberOfRetries}.");
return(AL_ReadData_Result.ALRes_DatTransferErrr);
}
m_statistic.IncStRxFrameCounter();
pData = new ReadDataEntity(_copy, pBlock);
TraceSource.TraceMessage(TraceEventType.Verbose, 191, $"ReadData succeeded for [{pStation}/{pBlock.startAddress}]");
return(AL_ReadData_Result.ALRes_Success);
}
/// <summary>
/// Transits frame and gets response. Response is analyzed to much the sent frame.
/// </summary>
/// <param name="Txmsg">Frame to be sent.</param>
/// <param name="Rxmsg">Received frame</param>
/// <param name="cRetries">Number of retries to get frame from remote unit.</param>
/// <returns>
/// ALRes_Success: Operation accomplished successfully
/// ALRes_DatTransferErrr: Data transfer is impossible because of a communication error – loss of
/// communication with a station
/// ALRes_DisInd: Disconnect indication – connection has been shut down remotely or lost because of
/// communication error. Data is unavailable
/// </returns>
private AL_ReadData_Result TxGetResponse(T_ALMessage Txmsg, out T_ALMessage Rxmsg, byte cRetries)
{
Rxmsg = null;
TGRState currState = TGRState.TxReq;
if (Txmsg == null)
{
AssemblyTraceEvent.Tracer.TraceEvent(TraceEventType.Information, 83, "ApplicationLayerMaster.TxGetResponse - Transmitted message cannot be null.");
return(AL_ReadData_Result.ALRes_DatTransferErrr);
}
while (true)
{
switch (currState)
{
case TGRState.TxReq:
Timer.WaitTimeout(m_protocol.GetProtocolParameters.InterframeGapSpan, InterfrarmeStopwatch);
switch (m_protocol.TransmitMessage(Txmsg))
{
case AL_ReadData_Result.ALRes_Success:
currState = TGRState.RxRes;
break;
case AL_ReadData_Result.ALRes_DisInd:
return(AL_ReadData_Result.ALRes_DisInd);
case AL_ReadData_Result.ALRes_DatTransferErrr:
return(AL_ReadData_Result.ALRes_DatTransferErrr);
}
break;
case TGRState.RxRes:
if (Txmsg == null)
{
AssemblyTraceEvent.Tracer.TraceEvent(TraceEventType.Information, 105, "ApplicationLayerMaster.TxGetResponse - Before: m_protocol.GetMessage( out Rxmsg, Txmsg ): Transmitted message cannot be null.");
return(AL_ReadData_Result.ALRes_DatTransferErrr);
}
AL_ReadData_Result res = m_protocol.GetMessage(out Rxmsg, Txmsg);
InterfrarmeStopwatch.Reset();
InterfrarmeStopwatch.Start();
switch (res)
{
case AL_ReadData_Result.ALRes_Success:
InterfrarmeStopwatch.Reset();
InterfrarmeStopwatch.Start();
ProtocolALMessage.CheckResponseResult lastCheckResult = Rxmsg.CheckResponseFrame(Txmsg);
switch (lastCheckResult)
{
case ProtocolALMessage.CheckResponseResult.CR_OK:
m_Statistic.IncStRxFrameCounter();
return(AL_ReadData_Result.ALRes_Success);
case ProtocolALMessage.CheckResponseResult.CR_SynchError:
m_Statistic.IncStRxSynchError();
break;
case ProtocolALMessage.CheckResponseResult.CR_Incomplete:
m_Statistic.IncStRxFragmentedCounter();
break;
case ProtocolALMessage.CheckResponseResult.CR_CRCError:
m_Statistic.IncStRxCRCErrorCounter();
break;
case ProtocolALMessage.CheckResponseResult.CR_Invalid:
m_Statistic.IncStRxInvalid();
break;
case ProtocolALMessage.CheckResponseResult.CR_NAK:
m_Statistic.IncStRxNAKCounter();
break;
}
if (!((IEnvelope)Rxmsg).InPool)
{
Rxmsg.ReturnEmptyEnvelope();
}
Rxmsg = null;
currState = TGRState.Retray;
break;
//return AL_ReadData_Result.ALRes_DatTransferErrr;
case AL_ReadData_Result.ALRes_DisInd:
if (Rxmsg != null)
{
if (!((IEnvelope)Rxmsg).InPool)
{
Rxmsg.ReturnEmptyEnvelope();
}
Rxmsg = null;
}
return(AL_ReadData_Result.ALRes_DisInd);
default:
currState = TGRState.Retray;
break;
}
break;
case TGRState.Retray:
if (Rxmsg != null)
{
if (!((IEnvelope)Rxmsg).InPool)
{
Rxmsg.ReturnEmptyEnvelope();
}
Rxmsg = null;
}
if (cRetries == 0)
{
return(AL_ReadData_Result.ALRes_DatTransferErrr);
}
cRetries--;
currState = TGRState.TxReq;
break;
}
}//while (true)
}