KNX/EIB How to convert a 4 byte value into EIS 11 (DPT13 - Energy)

[gjniewenhuijse]

We like to use an SIM-KNX module with an Arduino MicroController to develop a device to send Energy information from a dutch energysmartmeter to a KNX installation.

Do anyone know how to convert a 4 byte value into EIS 11 (DPT13 - Energy)?

[S. De Bruyne]

http://www.knx.org/fileadmin/downloa...07.00%20AS.zip

[gjniewenhuijse]

Falcon

Yes i know the document and writed some testcode in Visual C# with the FALCON SDK, but i can't send a right DPT13 packet..

Other datapoints as ON/OFF is no problem..

[S. De Bruyne]

This is funny. DPT 13.013 is a plain 32 bit signed integer, that is on the bus encoded and transmitted just as it is done in C#. It would not need any conversion at all...
So, if you have energy data in your module and it's encoded as a signed 32 bit integer and the unit is kWh, then it's good as it is.
What is exactly the problem?

[gjniewenhuijse]

I wrote the following code:

private void button2_Click(object sender, EventArgs e)
{
try
{
if (KnxComm.connected())
{
int curval = 1024;
string currentKwhHex = curval.ToString("X8");
MessageBox.Show(currentKwhHex + " : " + Int32.Parse(currentKwhHex, System.Globalization.NumberStyles.HexNumber));
// EIS11 DPT13
DeviceWriteError eError = KnxComm._ptrGroupDataTransfer.Write((object)"0x" + KnxComm.group2knx("8/7/2"),
(Priority)3,
6, //RoutingCount
false, //Lessthan7bits
curval
);

// EIS11 DPT13
eError = KnxComm._ptrGroupDataTransfer.Write((object)"0x" + KnxComm.group2knx("8/7/3"),
(Priority)3,
6, //RoutingCount
false, //Lessthan7bits
(object)"0x" + currentKwhHex.Substring(0, 2) + " 0x" + currentKwhHex.Substring(2, 2) + " 0x" + currentKwhHex.Substring(4, 2) + " 0x" + currentKwhHex.Substring(6, 2)
);
// extended error information
if (eError != DeviceWriteError.DeviceWriteErrorNoError)
{
// error message
Logging.writeLog("Error: group data write error");
MessageBox.Show("Error: group data write error");
}
}
else
{
MessageBox.Show("Geen connectie");
}
}
catch (Exception ex) // show error
{
Logging.writeLog(ex.Message);
MessageBox.Show("Error write group address!" + ex.Message);
}
}

}


---------------

int curval is an int32
when i send the value 1024 to address 8/7/2 and 8/7/3 i see on the busmonitor the following value:
00 00 04 00 | 1,43493E-42

I don't know why this value is sended. I only want to set an int32 on the bus, so my other software/hardware can see this value.

[S. De Bruyne]

Don't let the Busmonitor mislead you ... I have the impression that the HEX-value is correct, but that the Busmonitor thinks that it is a 4 octet float value instead of a 4 octet signed integer. I assume that's why it shows 1,43493E-42 instead of 1024.

[gjniewenhuijse]

Don't let the Busmonitor mislead you ... I have the impression that the HEX-value is correct, but that the Busmonitor thinks that it is a 4 octet float value instead of a 4 octet signed integer. I assume that's why it shows 1,43493E-42 instead of 1024.

Yes its a little bit weird. In the busmonitor i set its an 4 byte signed integer, but it looks like it goes wrong in the c# code.

Maybe it has something todo that i execute the code on a 64bit machine.

When i display the bus values in Domovea (Hager visualization), i have also weird values and not the one i send with my c# code.

[gjniewenhuijse]

Yes i found the problem, but not a solution yet

i have to use DPT 14.056 (4-octet float value) instead of the 4 bytes signed integer...

But how to decode this to send it with the falcon sdk..