private async Task ReadAsync(ModbusDevice device, ModbusFunctionCode functionCode, int zeroBasedOffset, int count, Action <MessageBufferSpan> actionWithReturnedBuffer, CancellationToken cancellationToken)
{
var requestContext = new ModbusTransportContext()
{
TransactionIdentifier = GetTransactionIdentifier()
};
await ModbusTransport.SendMessageAsync(requestContext,
(writer) =>
{
writer.Push(device.Address);
writer.Push((byte)functionCode);
writer.Push((byte)((zeroBasedOffset >> 8) & 0xFF));
writer.Push((byte)((zeroBasedOffset >> 0) & 0xFF));
writer.Push((byte)((count >> 8) & 0xFF));
writer.Push((byte)((count >> 0) & 0xFF));
}, cancellationToken);
MessageBufferSpan?receivedBuffer = null;
var responseContext = await ModbusTransport.ReceiveMessageAsync(
async (reader) =>
{
if (await reader.PushByteFromStreamAsync(cancellationToken) != device.Address)
{
throw new InvalidOperationException();
}
byte receivedFunctionCode = await reader.PushByteFromStreamAsync(cancellationToken);
if (receivedFunctionCode == ((byte)functionCode | 0x80))
{
var exceptionCode = (ModbusExceptionCode)await reader.PushByteFromStreamAsync(cancellationToken);
throw new ModbusException(exceptionCode);
}
if (receivedFunctionCode != (byte)functionCode)
{
throw new InvalidOperationException();
}
var byteCount = await reader.PushByteFromStreamAsync(cancellationToken);
await reader.PushFromStreamAsync(byteCount, cancellationToken);
receivedBuffer = new MessageBufferSpan(reader.Buffer, (ushort)(reader.Buffer.Length - byteCount), byteCount);
}, cancellationToken);
if (responseContext.TransactionIdentifier != requestContext.TransactionIdentifier)
{
throw new InvalidOperationException();
}
actionWithReturnedBuffer(receivedBuffer !);
}
private async Task <T> WriteAsync <T>(ModbusDevice device, ModbusFunctionCode functionCode, int zeroBasedOffset, Action <IMessageBufferWriter> writeAction, Func <IMessageBufferReader, Task <T> > readValueFunc, CancellationToken cancellationToken)
{
var requestContext = new ModbusTransportContext()
{
TransactionIdentifier = GetTransactionIdentifier()
};
await ModbusTransport.SendMessageAsync(requestContext,
(writer) =>
{
writer.Push(device.Address);
writer.Push((byte)functionCode);
writer.Push((byte)((zeroBasedOffset >> 8) & 0xFF));
writer.Push((byte)((zeroBasedOffset >> 0) & 0xFF));
writeAction(writer);
}, cancellationToken);
T returnedValue = default;
var responseContext = await ModbusTransport.ReceiveMessageAsync(
async (reader) =>
{
if (await reader.PushByteFromStreamAsync(cancellationToken) != device.Address)
{
throw new InvalidOperationException();
}
byte receivedFunctionCode = await reader.PushByteFromStreamAsync(cancellationToken);
if (receivedFunctionCode == ((byte)functionCode | 0x80))
{
var exceptionCode = (ModbusExceptionCode)await reader.PushByteFromStreamAsync(cancellationToken);
throw new ModbusException(exceptionCode);
}
if (receivedFunctionCode != (byte)functionCode)
{
throw new InvalidOperationException();
}
if (await reader.PushByteFromStreamAsync(cancellationToken) != zeroBasedOffset)
{
throw new InvalidOperationException();
}
returnedValue = await readValueFunc(reader);
}, cancellationToken);
if (requestContext.TransactionIdentifier != responseContext.TransactionIdentifier)
{
throw new InvalidOperationException();
}
return(returnedValue !);
}