private byte[] modbusRead(byte id, ushort addr, ushort length)
{
byte[] data = new byte[length];
// get the most significant digit
int pow = (int)Math.Pow(10, Math.Floor(Math.Log10(addr)));
int ldigit = (int)Math.Floor((double)addr / pow);
addr = (pow > 1) ? (ushort)(addr % pow) : addr;
// four operation type
switch (ldigit)
{
case 1:
socket.ReadCoils(1, id, addr, length, ref data);
return(data);
case 2:
socket.ReadDiscreteInputs(2, id, addr, length, ref data);
return(data);
case 3:
socket.ReadInputRegister(3, id, addr, length, ref data);
return(data);
case 4:
socket.ReadHoldingRegister(4, id, addr, length, ref data);
return(data);
default:
throw new Exception();
}
}