Problem in parse a frame from meter

By NGR0223 , 23 March, 2022

Forums

I am new to DLMS, I have some problem in parse the response frame while using the gurux.dlms.cpp.master.

I want to read the IC 0x15, the OBIS "0.0.40.0.0.255" and the attribute 3 by constructing the CGXDLMSObject, then I read it through the CGXCommunication::Read(). Part of code is as follows:

CGXDLMSObject *obj = new CGXDLMSObject(classId, ln);
std::vector<CGXByteBuffer> data;
int ret = comm.Read(obj, attr, nullptr, data);

I have got the correct response frame from the meter. But I want to get the payload of the frame. I have searched for the way to do it. The mothod in the link(https://www.gurux.fi/node/14896) seems does not work correctly. Part of code is as follows:

unsigned char *responseFrame = {0x00, 0x01, 0x00, 0x01, 0x00, 0x05, 0x00, 0x0B, 0xC4, 0x01,
0x81, 0x00, 0x02, 0x02, 0x0F, 0x05, 0x12, 0x00, 0x01}
CGXDLMSSecureClient client( // );
CGXReplyData payload;
CGXReplyData notify;
CGXByteBuffer reply;
reply.Set(responseFrame, lengthFrame);
if ((ret = client.GetData(reply, payload, notify) == 0)
{
cout << payload.GetData().ToHexString() << endl;
// 00 02 0F 05 12 00 01
}

So if i want to get the string "C4 01 81 00 02 02 0F 05 12 00 01", what should I modify my code or could you tell me a correct way.

Thanks!

Hi,

Don't use CGXDLMSObject. Use CGXDLMSRegister, CGXDLMSData, etc. instead. They will parse data and you don't need to do anything.

Something like this:
CGXDLMSRegister*obj = new CGXDLMSRegister(ln);

BR,
Mikko

Thank you for your reply.

I will try to generate the request frame through the method you had mentioned.

However, my question is how should I parse a unsigned char array with the response frame from meter, for example, to verify the intergrity of the response frame and get the payload of it.

Hi,

DLMS is a very complicated protocol and describing it shortly is not possible.
https://www.gurux.fi/DLMSInNutshell

Good thing is that DLMS is very well documented. You can get started if you read the following standard documents.

IEC 62056-47 COSEM transport layers for IPv4 networks
IEC 62056-53 COSEM application layer
IEC 62056-61 OBIS Object identification system

I strongly propose that you use Gurux open source libraries. It will save a lot of time.

BR,
Mikko

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Hi,

Thank you for your reply.

Hi,