private async Task HandleRequestAsync()
{
while (true)
{
Logger.Debug($"Begin reading header from Master at IP: {EndPoint}");
int readBytes = await Stream.ReadAsync(_mbapHeader, 0, 6).ConfigureAwait(false);
if (readBytes == 0)
{
Logger.Debug($"0 bytes read, Master at {EndPoint} has closed Socket connection.");
ModbusMasterTcpConnectionClosed?.Invoke(this, new TcpConnectionEventArgs(EndPoint));
return;
}
ushort frameLength = (ushort)IPAddress.HostToNetworkOrder(BitConverter.ToInt16(_mbapHeader, 4));
Logger.Debug($"Master at {EndPoint} sent header: \"{string.Join(", ", _mbapHeader)}\" with {frameLength} bytes in PDU");
_messageFrame = new byte[frameLength];
readBytes = await Stream.ReadAsync(_messageFrame, 0, frameLength).ConfigureAwait(false);
if (readBytes == 0)
{
Logger.Debug($"0 bytes read, Master at {EndPoint} has closed Socket connection.");
ModbusMasterTcpConnectionClosed?.Invoke(this, new TcpConnectionEventArgs(EndPoint));
return;
}
Logger.Debug($"Read frame from Master at {EndPoint} completed {readBytes} bytes");
byte[] frame = _mbapHeader.Concat(_messageFrame).ToArray();
Logger.Trace($"RX from Master at {EndPoint}: {string.Join(", ", frame)}");
var request = _modbusFactory.CreateModbusRequest(_messageFrame);
request.TransactionId = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(frame, 0));
IModbusSlave slave = _slaveNetwork.GetSlave(request.SlaveAddress);
if (slave != null)
{
//TODO: Determine if this is appropriate
// perform action and build response
IModbusMessage response = slave.ApplyRequest(request);
response.TransactionId = request.TransactionId;
// write response
byte[] responseFrame = Transport.BuildMessageFrame(response);
Logger.Information($"TX to Master at {EndPoint}: {string.Join(", ", responseFrame)}");
await Stream.WriteAsync(responseFrame, 0, responseFrame.Length).ConfigureAwait(false);
}
}
}
/// <summary>
/// Apply the request.
/// </summary>
/// <param name="request"></param>
protected IModbusMessage ApplyRequest(IModbusMessage request)
{
//Check for broadcast requests
if (request.SlaveAddress == 0)
{
//Grab each slave
foreach (var slave in _slaves.Values)
{
try
{
//Apply the request
slave.ApplyRequest(request);
}
catch (Exception /*ex*/)
{
//Logger.Error($"Error applying request to slave {slave.UnitId}: {ex.Message}");
}
}
}
else
{
//Attempt to find a slave for this address
IModbusSlave slave = GetSlave(request.SlaveAddress);
// only service requests addressed to our slaves
if (slave == null)
{
Console.WriteLine($"NModbus Slave Network ignoring request intended for NModbus Slave {request.SlaveAddress}");
}
else
{
// perform action
return(slave.ApplyRequest(request));
}
}
return(null);
}