public static byte[] Create(byte[] message, ErrorCode code)
{
MbapHeader header = MbapHeader.Decode(message);
byte funcCode = message[7];
byte msb = 8;
byte funcByte = (byte)(msb << 0x04 | funcCode);
byte errorCode = (byte)code;
header.Length = 2;
byte[] headerBytes = header.Encode();
byte[] remaining = new byte[] { funcByte, errorCode };
byte[] errorMsg = new byte[headerBytes.Length + remaining.Length];
Buffer.BlockCopy(headerBytes, 0, errorMsg, 0, headerBytes.Length);
Buffer.BlockCopy(remaining, 0, errorMsg, headerBytes.Length, remaining.Length);
return(errorMsg);
}
public static MbapHeader Decode(byte[] message)
{
if (message.Length < 7)
{
return(null);
}
MbapHeader header = new MbapHeader();
int index = 0;
header.TransactionId = (ushort)(message[index++] << 0x08 | message[index++]);
header.ProtocolId = (ushort)(message[index++] << 0x08 | message[index++]);
header.Length = (ushort)(message[index++] << 0x08 | message[index++]);
header.UnitId = Convert.ToByte(message[index]);
return(header);
}
public byte[] MapOut(byte[] message)
{
MbapHeader header = MbapHeader.Decode(message);
string key = GetProxyMap(header.UnitId, header.TransactionId);
if (cache.Contains(key))
{
Tuple <ushort, byte> tuple = (Tuple <ushort, byte>)cache[key];
header.TransactionId = tuple.Item1;
header.UnitId = tuple.Item2;
cache.Remove(key);
byte[] buffer = new byte[message.Length];
byte[] src = header.Encode();
Buffer.BlockCopy(src, 0, buffer, 0, src.Length);
Buffer.BlockCopy(message, src.Length, buffer, src.Length, message.Length - src.Length);
return(buffer);
}
return(null);
}
public byte[] MapIn(byte[] message, byte?alias)
{
MbapHeader header = MbapHeader.Decode(message);
ModbusTransaction tx = ModbusTransaction.Create();
ushort actualTx = header.TransactionId;
ushort proxyTx = tx.Id;
Tuple <ushort, byte> tuple = new Tuple <ushort, byte>(actualTx, header.UnitId);
byte unitId = header.UnitId == (alias ?? header.UnitId) ? header.UnitId : alias.Value;
header.UnitId = unitId;
header.TransactionId = proxyTx;
cache.Add(GetProxyMap(unitId, proxyTx), tuple, 20.0);
byte[] buffer = new byte[message.Length];
byte[] src = header.Encode();
Buffer.BlockCopy(src, 0, buffer, 0, src.Length);
Buffer.BlockCopy(message, src.Length, buffer, src.Length, message.Length - src.Length);
return(buffer);
}
