How to convert Byte Array to CGXDLMSVariant?

By Dmitry , 23 November, 2021

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Hi, Mikko!

I have QByteArray with data. I know type of this data. I need to convert it to CGXDLMSVariant.
I try:
uint16_t intVar = 333;
int len_intVar = sizeof(intVar);
QByteArray a;
a.resize(len_intVar);
memcpy(a.data(), &intVar, len_intVar); //convert to QByteArray
-------
// from QByteArray
CGXByteBuffer b;
b.Set(a.data(), a.size());
CGXDLMSVariant v(b);
v.ChangeType(DLMS_DATA_TYPE_UINT16);
But v is not equal 333.

Also i tried:
CGXDLMSVariant v1((unsigned char*)a.data(), a.size(), DLMS_DATA_TYPE_UINT16);
but failed. v1 is not 333.

Could you please write an example?
Thanks!

Hi,

Do like this if there is no data type in the byte array and it's just raw data.

CGXByteBuffer bb;
bb.SetInt16(333);
CGXDLMSVariant v;
CGXDLMSClient::ChangeType(bb, DLMS_DATA_TYPE_UINT16, v);

BR,
Mikko

Hi, Mikko!

Hi, Mikko!
I try:
const std::string obis("0000636207ff");
CGXByteBuffer bb;
bb.SetHexString(obis);
CGXDLMSVariant v;
CGXDLMSClient::ChangeType(bb, DLMS_DATA_TYPE_OCTET_STRING, v);
qDebug() << "v:" << v.ToString().c_str();
And get output: v: 0.0.99.98.7.255. //type: DLMS_DATA_TYPE_STRING but i pass to method DLMS_DATA_TYPE_OCTET_STRING.
I need v as DLMS_DATA_TYPE_OCTET_STRING 0000636207ff which size = 6 bytes. What i'm doing wrong?

Thanks!

This code works correctly:

This code works correctly:
QByteArray arr(QByteArray::fromHex(obis.c_str()));
CGXByteBuffer bb1;
bb1.Set(arr.data(), arr.size());
CGXDLMSVariant v1(bb1);
qDebug() << "v1:" << v1.ToString().c_str() << "type:" << v1.vt;

CGXByteBuffer bb2;
v1.GetBytes(bb2);
auto ss=bb2.ToHexString(false);
qDebug() << "ss:" << ss.c_str();

Output:
v1: 00 00 63 62 07 FF type: 9 // 9 - DLMS_DATA_TYPE_OCTET_STRING
ss: 0000636207FF

Hi Dmitry,

The second topic works correctly because v1.ToString converts a byte array to hex string.

If you want to convert a logical name to a string, I propose that you use GXHelpers::GetLogicalName-method for that.

BR,
Mikko

Thanks for you reply. Data

Thanks for you reply. Data may be anything. Not just logical name.

Hi,

Do you want to convert it to the string or hex string?

BR,
Mikko

I would like this:

I would like this:
input:
std::string hex_str("0000636207ff");
output:
CGXDLMSVariant v;
v.vt == DLMS_DATA_TYPE_OCTET_STRING;
v.byteArr contains {00, 00, 63, 62, 07, ff}
v.GetSize() == 6

I write function for this:
CGXDLMSVariant hex_string_to_octet_string(std::string_view s)
{
const QByteArray arr(QByteArray::fromHex(s.data()));
CGXByteBuffer bb;
bb.Set(arr.data(), static_cast<unsigned long>(arr.size()));
CGXDLMSVariant v(bb);
return v;
}

but i think it may be done with Gurux.cpp.

Hi,

You can do it like this:
CGXByteBuffer bb;
bb.SetHexString("0000636207ff");
CGXDLMSVariant v1(bb);

BR,
Mikko

How to convert Byte Array to CGXDLMSVariant?

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