Problems when writing values that are not bit

[GerardoPG]

Hi,
Now i'm able to read & write bits: no problem!.

But, I can't write values to the PLC. I don't know what i'm doing wrong. I'm programming in .net 2.0 + C#.

Ok, I'm tetsting writin to the following directions:
1) DB4.DBW2 and the value is a simple 4.
2) DB6.DBD4 and the value is a simple 7.

Using my function it's like this:
WriteToPLC(4,2,2,"4");
WriteToPLC(6,4,4,"7");

My functions is like this one:

public void WriteToPLC(int DBNumber, int Start, int Len, string Data) {
  int res = 0;
  try {
    int a = Convert.ToInt32(Data);
    byte[] aa = BitConverter.GetBytes(libnodave.daveSwapIed_32(a));
    res = dc.writeBytes(libnodave.daveDB, DBNumber, Start, Len, ada);
    if (res != 0) {
      throw new Exception(string.Format("[{0}] [Exception] Error writing to PLC IP: {1} DB: {2} Start: {3} Len: {4} Data: {5} libnodaveError: {6}", System.Reflection.MethodBase.GetCurrentMethod().Name, this._PLC_IP, DBNumber, Start, Len, Data, libnodave.daveStrerror(res)));
    }
  }
  catch (Exception ex) {
     // code for catch
  }
}

Can anybody help me about what's wrong?? thanks in advance!!

GerardoPG.

[GerardoPG]

OK buddys,
My problem now is shorter than before... I'm just having problems when reading & writing to DWord or floating numbers...

the problem is that libnodave responses res = 0, but the values weren't written. Any trick-tip-help??

thanks in advance!!

switch (TheValues.TagTyp)  // tag type, is a flagtype
{
    case 3: // word --->>> OK!!!
        res = dc.writeBytes(libnodave.daveDB, TheValues.DBNumber, TheValues.Start, TheValues.Len, BitConverter.GetBytes(libnodave.daveSwapIed_16(Convert.ToInt16(TheValues.Data.Trim()))));
        break;
    case 5: // DWord ---->>> N-OK!!
        float swapVal = libnodave.toPLCfloat(float.Parse(TheValues.Data));
        byte[] bytes = BitConverter.GetBytes(swapVal);
        res = dc.writeBytes(libnodave.daveDB, TheValues.DBNumber, TheValues.Start, TheValues.Len, bytes);
        break;
    default:
        res = -5;
        break;
}

-----
GerardoPG

[afk]

Do you want to write a DWord (Int32 or UInt32) or a Float to the PLC ?

Axel

[GerardoPG]

Hi Axel,
First, thanks again for your help. You always helped me in the past and now.

Well, I've resolved my problem, and yes: when trying to write Word, DWord and Float to the PLC. I don't why my solution works, I hope you can help me understand a bit better.

I have a funtion named "WriteToPLC", this write data that it's not Bit type (I use another function for that purposes). This is the code:
public bool WriteToPLC(SWriteS7Data TheValues) {
    int res = 0;
    try {
        /*
            "TheValues.TagTyp" could be any of the next data column "Tp":
            Tp  Desc        Length
            1   Byte        1        
            2   Bit         1        
            3   Word        2        
            4   Long/Float  4        
            5   DWord       4        
            6   int         2        
            7   Dint        4
         */

        switch (TheValues.TagTyp) {
            case 3: // word
                res = dc.writeBytes(libnodave.daveDB, TheValues.DBNumber, TheValues.Start, TheValues.Len, BitConverter.GetBytes(libnodave.daveSwapIed_16(Convert.ToInt16(TheValues.Data.Trim()))));
                break;
            case 5: // DWord
                float swapVal1 = float.Parse(TheValues.Data);
                //////float swapVal = libnodave.toPLCfloat(0.0f + swapVal1 + 0.0f);
                byte[] bytes = BitConverter.GetBytes(libnodave.toPLCfloat(0.0f + swapVal1 + 0.0f));
                byte t1, t2, t3, t4;
                t1 = bytes[0]; t2 = bytes[1]; t3 = bytes[2]; t4 = bytes[3];
                bytes[0] = t4; bytes[1] = t3; bytes[2] = t2; bytes[3] = t1;
                res = dc.writeBytes(libnodave.daveDB, TheValues.DBNumber, TheValues.Start, TheValues.Len, bytes);
                break;
            default:
                res = -5;
                break;
        }

        if (res != 0) {
            throw new Exception(string.Format("Error al intentar escribir: [{0}] libnodaveError: {1}", TheValues.ToString(), libnodave.daveStrerror(res)));
        }
    }
    catch (Exception ex) {
        Trace.WriteLine(string.Format("[{0}] [Exception] Error writing to PLC IP: {1} ExMsg: {2}", System.Reflection.MethodBase.GetCurrentMethod().Name, this._PLC_IP, ex.Message));
        return false;
    }
    return true;
}

You can see in my code that when I write a value of type 5 ("DWord") too I can write a "Float" value. Well, first I use the recommended method for write (get the value in a data type correctly, next use the libnodave.toPLCfloat function and get the bytes. But, finally I always have to, again, swap the values.

If I don't do that no values are written to the PLC. So, this code is actually running for me. And as you can see, I can write too values for Int16 (Word) with no problems.

Can you, Axel, help understand why this code works?

And again, thanks for your support!

Gerardo.

[afk]

I'm not shure if I really understand what you want to do in your code. As I understand you want to write values of type Word (Tp=3), Float (Tp=4) and DWord (TP=5), but your code handles only with Tp=3 for Words and Tp=5 for Floats, and the second part is wrong in my opinion. I think for Tp=5 (DWords) you should use a similar code as for Words, but with "libnodave.daveSwapIed_32(Convert.ToInt32".

I think your code for Floats is working because BitConverter.GetBytes seems to swap the bytes also, thus you have to swap the bytes afterwards again, but I think you should change your case-condition to Tp=4.

Axel