protected override async Task <IModbusResponse> ReadResponseAsync <TResponse>(CancellationToken token = default)
{
var buffer = await PipeResource.ReadAsync(MbapHeaderSizeOnResponse, token).ConfigureAwait(false);
var frameDataLength = (ushort)IPAddress.HostToNetworkOrder(BitConverter.ToInt16(buffer.Slice(4, 2).ToSpan()));
var totalLength = MbapHeaderSizeOnResponse + frameDataLength;
if (buffer.Length < totalLength)
{
PipeResource.MarkExamined(buffer);
buffer = await PipeResource.ReadAsync(totalLength, token).ConfigureAwait(false);
}
var processedSequence = buffer.Slice(0, MbapHeaderSizeOnResponse + frameDataLength);
var response = ModbusResponseFactory.CreateResponse <TResponse>(
processedSequence
.Slice(MbapHeaderSizeOnResponse, processedSequence.Length - MbapHeaderSizeOnResponse)
.ToSpan());
response.TransactionId = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(processedSequence.Slice(0, 2).ToSpan()));
PipeResource.MarkConsumed(processedSequence);
return(response);
}
protected override async Task <IModbusResponse> ReadResponseAsync <TResponse>(CancellationToken token = default)
{
var buffer = await PipeResource.ReadAsync(ResponseFrameStartSize, token).ConfigureAwait(false);
var lengthSequence = buffer.Slice(0, ResponseFrameStartSize);
var frameDataLength = GetResponseDataSize(lengthSequence.ToSpan());
var totalLength = ResponseFrameStartSize + frameDataLength + CrcSize;
if (buffer.Length < totalLength)
{
PipeResource.MarkExamined(lengthSequence);
buffer = await PipeResource.ReadAsync(totalLength, token).ConfigureAwait(false);
}
var processedSequence = buffer.Slice(0, totalLength);
var expectedCrc = crcCalculator.Calculate(processedSequence.Slice(0, totalLength - CrcSize).ToMemory());
var actualCrc = BitConverter.ToUInt16(processedSequence.Slice(totalLength - CrcSize, CrcSize).ToSpan());
if (actualCrc != expectedCrc)
{
PipeResource.MarkConsumed(processedSequence);
throw new IOException($"Received unexpected CRC. Expected: {expectedCrc}. Received: {actualCrc}.");
}
var response = ModbusResponseFactory.CreateResponse <TResponse>(processedSequence.ToSpan());
PipeResource.MarkConsumed(processedSequence);
return(response);
}