/// <summary>
/// Entry-point for submitting a query to the remote device
/// </summary>
/// <param name="data"></param>
/// <returns></returns>
public CommResponse Query(ClientCommData data)
{
lock (this.Port)
{
try
{
//set the proper parameters to the port
this.Port.BaudRate = this.Setting.BaudRate;
this.Port.Parity = this.Setting.Parity;
this.Port.DataBits = this.Setting.DataBits;
this.Port.StopBits = this.Setting.StopBits;
this.Port.RtsEnable = this.Setting.RtsEnable;
}
catch (Exception ex)
{
return(new CommResponse(
data,
CommResponse.Critical,
ex.Message));
}
//convert the request data as an ordinary byte array
byte[] outgoing = ((IByteArray)data.OutgoingData).Data;
//create a writer for accumulate the incoming data
var incoming = new ByteArrayWriter();
const int tempSize = 64;
var temp = new byte[tempSize];
//retries loop
for (int attempt = 0, retries = data.Retries; attempt < retries; attempt++)
{
try
{
//flush any residual content
this.Port
.DiscardInBuffer();
this.Port
.DiscardOutBuffer();
#if NET45
System.Diagnostics.Trace.WriteLine("TX: " + ByteArrayHelpers.ToHex(outgoing));
#endif
//phyiscal writing
this.Port
.Write(outgoing, 0, outgoing.Length);
}
catch (Exception ex)
{
return(new CommResponse(
data,
CommResponse.Critical,
ex.Message));
}
incoming.Drop();
//start the local timer
bool timeoutExpired;
int totalTimeout = this.Latency + data.Timeout;
using (Timer timer = new Timer(
_ => timeoutExpired = true,
state: null,
dueTime: totalTimeout,
period: Timeout.Infinite))
{
//reception loop, until a valid response or timeout
timeoutExpired = false;
while (timeoutExpired == false)
{
int length = this.Port.BytesToRead;
if (length > 0)
{
if (length > tempSize)
{
length = tempSize;
}
try
{
//read the incoming data from the physical port
this.Port
.Read(temp, 0, length);
}
catch (Exception ex)
{
return(new CommResponse(
data,
CommResponse.Critical,
ex.Message));
}
//append data to the writer
incoming.WriteBytes(
temp,
0,
length);
//try to decode the stream
data.IncomingData = incoming.ToReader();
#if NET45
System.Diagnostics.Trace.WriteLine("RX: " + ByteArrayHelpers.ToHex(incoming.ToByteArray()));
#endif
CommResponse result = data
.OwnerProtocol
.Codec
.ClientDecode(data);
//exit whether any concrete result: either good or bad
if (result.Status == CommResponse.Ack)
{
return(result);
}
else if (result.Status == CommResponse.Critical)
{
return(result);
}
else if (result.Status != CommResponse.Unknown)
{
break;
}
}
Thread.Sleep(0);
//stop immediately if the host asked to abort
//TODO
}
} //using (timer)
} //for
//no attempt was successful
return(new CommResponse(
data,
CommResponse.Critical));
} //lock
}
