/// <summary>
/// Initializes the request ADU and calculates the response length.
/// </summary>
public virtual void InitReqADU(byte devAddr, TransMode transMode)
{
if (ReqPDU == null)
{
return;
}
int pduLen = ReqPDU.Length;
switch (transMode)
{
case TransMode.RTU:
ReqADU = new byte[pduLen + 3];
ReqADU[0] = devAddr;
Buffer.BlockCopy(ReqPDU, 0, ReqADU, 1, ReqPDU.Length);
ushort crc = ModbusUtils.CRC16(ReqADU, 0, pduLen + 1);
ReqADU[pduLen + 1] = (byte)(crc % 256);
ReqADU[pduLen + 2] = (byte)(crc / 256);
RespAduLen = RespPduLen + 3;
break;
case TransMode.ASCII:
byte[] aduBuf = new byte[pduLen + 2];
aduBuf[0] = devAddr;
Buffer.BlockCopy(ReqPDU, 0, aduBuf, 1, ReqPDU.Length);
aduBuf[pduLen + 1] = ModbusUtils.LRC(aduBuf, 0, pduLen + 1);
StringBuilder sbADU = new StringBuilder();
foreach (byte b in aduBuf)
{
sbADU.Append(b.ToString("X2"));
}
ReqADU = Encoding.ASCII.GetBytes(sbADU.ToString());
ReqStr = ModbusUtils.Colon + sbADU;
RespAduLen = RespPduLen + 2;
break;
default: // TransModes.TCP
ReqADU = new byte[pduLen + 7];
ReqADU[0] = 0;
ReqADU[1] = 0;
ReqADU[2] = 0;
ReqADU[3] = 0;
ReqADU[4] = (byte)((pduLen + 1) / 256);
ReqADU[5] = (byte)((pduLen + 1) % 256);
ReqADU[6] = devAddr;
Buffer.BlockCopy(ReqPDU, 0, ReqADU, 7, ReqPDU.Length);
RespAduLen = RespPduLen + 7;
break;
}
}
/// <summary>
/// Performs a request in the ASCII mode.
/// </summary>
protected bool AsciiRequest(DataUnit dataUnit)
{
bool result = false;
// send request
log.WriteLine(dataUnit.ReqDescr);
Connection.WriteLine(dataUnit.ReqStr, out string logText);
log.WriteLine(logText);
// receive response
string line = Connection.ReadLine(Timeout, out logText);
log.WriteLine(logText);
int lineLen = line == null ? 0 : line.Length;
if (lineLen >= 3)
{
int aduLen = (lineLen - 1) / 2;
if (aduLen == dataUnit.RespAduLen && lineLen % 2 == 1)
{
// receive response ADU
byte[] aduBuf = new byte[aduLen];
bool parseOK = true;
for (int i = 0, j = 1; i < aduLen && parseOK; i++, j += 2)
{
try
{
aduBuf[i] = byte.Parse(line.Substring(j, 2), NumberStyles.HexNumber);
}
catch
{
log.WriteLine(ModbusPhrases.IncorrectSymbol);
parseOK = false;
}
}
if (parseOK)
{
if (aduBuf[aduLen - 1] == ModbusUtils.LRC(aduBuf, 0, aduLen - 1))
{
// decode response
if (dataUnit.DecodeRespPDU(aduBuf, 1, aduLen - 2, out string errMsg))
{
log.WriteLine(ModbusPhrases.OK);
result = true;
}
else
{
log.WriteLine(errMsg + "!");
}
}
else
{
log.WriteLine(ModbusPhrases.LrcError);
}
}
}
else
{
log.WriteLine(ModbusPhrases.IncorrectAduLength);
}
}
else
{
log.WriteLine(ModbusPhrases.CommErrorWithExclamation);
}
return(result);
}