How to read / Write UDT From PLC SIEMENS (UA_EXTENSIONOBJECT_ENCODED_BYTESTRING)

[Mattia Guerra]

Hi everyone,

I'm trying to read an UDT from a Siemens PLC but I'm not able to do this. So I need your help.

Below is the code I wrote and the contents of the variable after reading.

UA_Variant *val = UA_Variant_new();
UA_Variant_init(val);

UA_Client_readValueAttribute(client, UA_NODEID_STRING(3, "\"DB_OPC_UA\".\"UDT\""), val);

UA_ExtensionObject * UA_UDT = (UA_ExtensionObject *)val->data;

The UDT is made up of the following data

How can I get the value of INTEGER_VALUE and FLOAT_VALUE from the ExtensionObject?

Thanks for your precious help!!

Best regards,

Mattia

[Matthias Konnerth]

Hi Mattia,

there is an example doing a similar thing: https://github.com/open62541/open62541/tree/master/examples/custom_datatype

There a "PointType" is registered at the client for correctly decoding the extension object.

Best regards,

Matthias.

[Mattia Guerra]

Hi Matthias,

I tried to modify the example but it does not work .I have attached the files modified by me. I think there's something wrong but I do not understand what.

May you help me?

Thanks so mouch

[András Penk]

I have the same problem. I was trying to do the same as in the example but i only got zeros back. I am trying to read from a Siemens PLC Simulator running in TIA Portal.