ReadMultiVars - Error when item not available in CPU

[Anonymous]

Why isn't the error code returned in de S7DataItem[] array when a ReadMultiVar is requested with an address location which is not available in the CPU ??
Tag DB15.DBW0 is in the list but not in the CPU --> returns value 0 but no error !!
The S7DataItem.Return = 0

Best regards,
Andy

[Davide Nardella]

Release ?
OS ?
CPU (Architecture) ?
Wrapper ?
I don't have the cristal ball ;)

[Anonymous]

Hello,

Release : 1.3.1
OS : Windows 8.1
CPU : x64
Wrapper : dot.net -> snap7.net.cs

Best regards,
Andy

[Davide Nardella]

I redesigned snap7.net.cs due to many issues related to GC :(

In a few days I will release Snap7 1.4.0 which contains a new release of .net wrapper.
In meantime in attach you find the new snap7.net.cs if you would like to test.

Some notes:

1 -----------------------------------------------------------------
The Read/write Multivars was changed : now there is the class S7Multivar which makes it easier and safer operations.
Into the full release you will find a complete WinForm C# demo.

Example of usage:

    public void DBMultiRead()
    {
        // Reader Instance
        S7MultiVar Reader = new S7MultiVar(Client);

        TxtRes_A.Text = "";
        TxtRes_B.Text = "";
        TxtRes_C.Text = "";

        int DBNumber_A = System.Convert.ToInt32(TxtDB_A.Text);
        int DBNumber_B = System.Convert.ToInt32(TxtDB_B.Text);
        int DBNumber_C = System.Convert.ToInt32(TxtDB_C.Text);

        // Add Items def.
        Reader.Add(S7Client.S7AreaDB, S7Client.S7WLByte, DBNumber_A, 0, 16, ref DB_A);
        Reader.Add(S7Client.S7AreaDB, S7Client.S7WLByte, DBNumber_B, 0, 16, ref DB_B);
        Reader.Add(S7Client.S7AreaDB, S7Client.S7WLByte, DBNumber_C, 0, 16, ref DB_C);
        // Performs the Read
        int Result = Reader.Read();

        // Dumps the data and shows the results
        ShowResult(Result);


        TxtRes_A.Text = Client.ErrorText(Reader.Results[0]);
        if (Reader.Results[0] == 0)
            Dump(TxtDump_A, DB_A, 16);
        else
            TxtDump_A.Text = "< No Data Available >";

        TxtRes_B.Text = Client.ErrorText(Reader.Results[1]);
        if (Reader.Results[1] == 0)
            Dump(TxtDump_B, DB_B, 16);
        else
            TxtDump_B.Text = "< No Data Available >";

        TxtRes_C.Text = Client.ErrorText(Reader.Results[2]);
        if (Reader.Results[2] == 0)
            Dump(TxtDump_C, DB_C, 16);
        else
            TxtDump_C.Text = "< No Data Available >";
    }

DB_A, DB_B and DB_C are 3 array of byte.

2 -----------------------------------------------------------------
Tere are many also helper functions : now ALL S7 types are handled (including 64 bit types of S71500)

Let me know...

[Anonymous]

Hello,

amazing how fast you're responding....
I just tested the readmultivar class and it is working.
I now get an 'Address out of range' error when item is not available in the CPU.

Another improvement would be to let the new S7MultiVarClass handle a split read, when amount of requested items > PDU Size.

I will try to work this out, and send you a testversion.

Thanks,

Andy

[Davide Nardella]

Mmmm... I don't know if that's possible.
The MultiRead/Write uses a specific protocol function which is limited, by design, to the PDU size.
Unless to write a "splittable" MRWrite.
Consider that the advantage of this fun. is to transfer more and small tags using a single transaction.
All remaining functions already split automatically the tags.
I don't know if the increasing complexity could lead to a real speed benefit : in any case you can transfer only "PDU" size bytes at time.

Nevertheless you are welcome to test and propose new solutions of course ;)

Regards
Dave