ReadWriteDenied on STRING Object

Hello,

I have a DLMS server running on a 32-bit MCU and a DLMS host also running on a 32-bit MCU, communicating via PLC. Both work correctly: I have created several objects on the server and can successfully connect, get the association view, perform read/write operations, and close the connection properly.

The issue begins when I define a new object called uInvControl. When I perform a read operation, everything works correctly — I’m able to read the object and receive its data without any problems. But when i perform a write operation:
C1 01 C1 00 01 01 00 2A 00 05 FF 02 00 0A 05 00 00 00 00 00
<SetRequest>
<SetRequestNormal>
<!--Priority: HIGH ServiceClass: CONFIRMED invokeID: 1-->
<InvokeIdAndPriority Value="C1" />
<AttributeDescriptor>
<!--DATA-->
<ClassId Value="0001" />
<!--1.0.42.0.5.255-->
<InstanceId Value="01002A0005FF" />
<AttributeId Value="02" />
</AttributeDescriptor>
<Value>
<String Value="

I receive from the server "ReadWriteDenied":
C5 01 C1 03
<SetResponse>
<SetResponseNormal>
<!--Priority: HIGH ServiceClass: CONFIRMED invokeID: 1-->
<InvokeIdAndPriority Value="C1" />
<Result Value="ReadWriteDenied" />
</SetResponseNormal>
</SetResponse>

To give some context, here are the more relevants parts about this object on the server.
I add this object to my list as follows:

gxObject* ALL_OBJECTS[] = { BASE(associationLow), BASE(myDATA), BASE(pvPower1), BASE(pvPower2), BASE(pvPower3), BASE(pvPower4), BASE(uInvControl) };

And I register the object using this function:

int addDataObject()
{
int ret;
const unsigned char ln[6] = { 1, 0, 99, 199, 0, 255 }; // myDATA
const unsigned char ln1[6] = { 1, 0, 42, 0, 5, 255 }; // uInvControl
if ((ret = INIT_OBJECT(myDATA, DLMS_OBJECT_TYPE_DATA, ln)) == 0 &&
(ret = INIT_OBJECT(uInvControl, DLMS_OBJECT_TYPE_DATA, ln1)) == 0)
{
GX_STRING(myDATA.value, (uint8_t*)myDATAValue, sizeof(myDATAValue));
GX_STRING(uInvControl.value, (uint8_t*)uInvControlValue, sizeof(uInvControlValue));
}
return ret;
}

In the svr_getAttributeAccess() function, I'm correctly configuring the object access as DLMS_ACCESS_MODE_READ_WRITE.

After debugging deeply, I identified the root cause. In the dlms.c file, within the getString() function:

int getString(gxByteBuffer* buff, gxDataInfo* info, unsigned char knownType, dlmsVARIANT* value)

The issue occurs because value->capacity < len, which causes it to return DLMS_ERROR_CODE_OUTOFMEMORY. This error then propagates through the server.c file in the svr_handleSetRequest() function, resulting in:

p.status = DLMS_ERROR_CODE_READ_WRITE_DENIED;

I've also tried using GXDLMS Director as a host, and the same issue occurs:

"Exception Response: Service not allowed"

Could you please advise on how to solve this issue?

Thank you so much.

Pablo