//TODO: Evaluate ReadHoldingRegisters return type. Should this be words? Bytes? something else?
// At the core of the protocol, this is really returning words. The words can be interpreted
// as floating point, integers, unsigned, etc.
public IEnumerable <Int16> ReadHoldingRegisters(Int16 startRegister, Int16 count)
{
List <byte> mbPacket = new List <byte>();
mbPacket.Add(0x03);
mbPacket.AddRange(startRegister.GetBytes());
mbPacket.AddRange(count.GetBytes());
MBAP mbap = MBAP.Create((Int16)(mbPacket.Count + 1), 0);
mbPacket.InsertRange(0, mbap.GetBytes());
tcpClient.GetStream().Write(mbPacket.ToArray(), 0, mbPacket.Count);
byte[] readBuffer = new byte[500];
tcpClient.GetStream().Read(readBuffer, 0, 500);
int returnCount = (int)readBuffer[8];
List <Int16> returnList = new List <short>();
for (int i = 9; i < 9 + returnCount; i += 2)
{
returnList.Add(Int16Extensions.FromBytes(readBuffer[i], readBuffer[i + 1]));
}
return(returnList);
}
public override ModbusTCPMessage Process(IMemoryModel memory)
{
int address = Int16Extensions.FromBytes(PDU.Data.First(), PDU.Data.Skip(1).First());
int length = Int16Extensions.FromBytes(PDU.Data.Skip(2).First(), PDU.Data.Skip(3).First());
try
{
var values = memory.Read4x(address, length);
ProtocolDataUnit pdu = PDU.ValidResponse(
new byte[]
{ (byte)(values.Count() * 2) }
.Concat(values.SelectMany(v => v.GetBytes())));
ModbusTCPMessage reply = Create(
MBAP.Create((byte)(pdu.GetBytes().Count() + 1), ApplicationHeader.UnitID),
pdu);
return(reply);
}
catch
{
ProtocolDataUnit pdu = PDU.ErrorResponse(new byte[] { 0x01 });
ModbusTCPMessage reply = Create(
MBAP.Create((byte)(pdu.GetBytes().Count() + 1), ApplicationHeader.UnitID),
pdu);
return(reply);
}
}
private Int16 StartAddress()
{
byte high = PDU.Data.First();
byte low = PDU.Data.Skip(1).First();
return(Int16Extensions.FromBytes(high, low));
}
private IEnumerable <short> ParseValues()
{
List <short> values = new List <short>();
var length = PDU.Data.Skip(4).First();
var dataBlock = PDU.Data.Skip(5);
for (int i = 0; i < length / 2; i++)
{
values.Add(Int16Extensions.FromBytes(
dataBlock.Skip(i * 2).First(),
dataBlock.Skip(i * 2 + 1).First()));
}
return(values);
}
protected MBAP(IEnumerable <byte> message)
{
_length = Int16Extensions.FromBytes(message.Skip(4).First(), message.Skip(5).First());
UnitID = message.Skip(6).First();
}