public void Append(ushort value, Endianness16 endianness = Endianness16.AB)
{
switch (endianness)
{
case Endianness16.AB:
_bytes.Add((byte)(value >> 8));
_bytes.Add((byte)(value & 0xff));
break;
case Endianness16.BA:
_bytes.Add((byte)(value & 0xff));
_bytes.Add((byte)(value >> 8));
break;
default:
throw new ArgumentException("Invalid endianness", "endianness");
}
}
public ushort ReadUShort(int offset, Endianness16 endianness = Endianness16.AB)
{
ushort result = 0;
switch (endianness)
{
case Endianness16.AB:
result |= (ushort)(_bytes[offset] << 8);
result |= _bytes[offset + 1];
break;
case Endianness16.BA:
result |= _bytes[offset];
result |= (ushort)(_bytes[offset + 1] << 8);
break;
default:
throw new ArgumentException("Invalid endianness", "endianness");
}
return(result);
}
public void Append(short value, Endianness16 endianness = Endianness16.AB)
{
Append((ushort)value, endianness);
}
public ushort[] ReadHoldingRegisters(byte unitAdr, ushort regAdr, ushort regCount, Endianness16 endianness = Endianness16.AB)
{
var builder = new MessageBuilder();
builder.Append(unitAdr);
builder.Append(0x03);
builder.Append(regAdr);
builder.Append(regCount);
byte[] resp = new byte[256];
int respLength = SendAndRecv(builder.ToArray(), resp, out int offset);
var reader = new MessageReader(resp, offset, respLength);
byte recvUnitAdr = reader.ReadByte();
if (recvUnitAdr != unitAdr)
{
throw new FormatException($"Unexpected unit address ({recvUnitAdr} != {unitAdr}).");
}
byte recvFuncCode = reader.ReadByte();
if ((recvFuncCode & 0x80) != 0)
{
throw new ModbusException(reader.ReadByte());
}
if (recvFuncCode != 0x03)
{
throw new FormatException($"Unexpected function code ({recvFuncCode} != 3).");
}
if (reader.Count != 3 + 2 * regCount)
{
throw new FormatException($"Modbus response wrong length for 0x03 ({reader.Count} != {3 + 2 * regCount}).");
}
byte recvByteCount = reader.ReadByte();
if (recvByteCount != 2 * regCount)
{
throw new FormatException($"Invalid byte count ({recvByteCount} != {2 * regCount}).");
}
ushort[] result = new ushort[regCount];
for (int i = 0; i < regCount; i++)
{
result[i] = reader.ReadUShort(endianness);
}
return(result);
}
