Can we create a opcua server that can generate data of complex datatypes?

[prathik-quartic]

Can we add variables of different opcua core datatypes like DataTime, AxisInformation?
I have tried adding it like this. It's not working and it's probably not the right way to go.

    node1 = myobj.add_variable("ns=2;s=Local.iCIR.Probe1.LastSampleTime", "Last_Sample_Time" , datetime.now(pytz.utc).strftime('%Y:%m:%d %H:%M:%S %Z'), datatype=ua.ObjectIds.DateTime)
    node2 = myobj.add_variable("ns=2;s=Local.iCIR.Probe1.SpectraRaw", "Y_Axis" , [numpy.random.uniform(0.01, 50.02) for i in range(1,498)], datatype=ua.ObjectIds.Double)
    units = ua.uaprotocol_auto.AxisInformation()
    units.EngineeringUnits = "EUInformation"
    units.UnitId = 0
    units.DisplayName = "cm-1"
    units.Description = "cm-1"
    units.AxisScaleType="AxisScaleEnumeration"
    units.name="Linear"
    units.ordinal=0
    units.AxisSteps=[numpy.random.uniform(0.01, 2458.02) for i in range(1,498)]
    node3 = myobj.add_variable("ns=2;s=Local.iCIR.Probe1.SpectraRaw.XAxisDefinition", "X_Axis" , ua.Variant(units), datatype=ua.ObjectIds.AxisInformation)
    node1.set_writable()
    node2.set_writable()
    node3.set_writable()

Can someone please tell me if there is a way we can achieve this?

[oroulet]

it looks correct, maybe there is a typo somewhere...
you can also look at that example: https://github.com/FreeOpcUa/opcua-asyncio/blob/master/examples/server-create-custom-structures.py

[prathik-quartic]

Thank you for the response.
The issue is when the client is accessing the value of complex types like AxisInformation.

ERROR:opcua.server.binary_server_asyncio:Exception raised while parsing message from client, closing
Traceback (most recent call last):
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/server/binary_server_asyncio.py", line 75, in _process_data
    ret = self.processor.process(hdr, buf)
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/server/uaprocessor.py", line 96, in process
    return self.process_message(msg.SequenceHeader(), msg.body())
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/server/uaprocessor.py", line 116, in process_message
    return self._process_message(typeid, requesthdr, seqhdr, body)
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/server/uaprocessor.py", line 195, in _process_message
    self.send_response(requesthdr.RequestHandle, seqhdr, response)
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/server/uaprocessor.py", line 47, in send_response
    struct_to_binary(response), message_type=msgtype, request_id=seqhdr.RequestId)
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 256, in struct_to_binary
    packet.append(list_to_binary(uatype[6:], val))
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 296, in list_to_binary
    pack = [to_binary(uatype, el) for el in val]
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 296, in <listcomp>
    pack = [to_binary(uatype, el) for el in val]
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 274, in to_binary
    return pack_uatype(vtype, val)
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 194, in pack_uatype
    return struct_to_binary(value)
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 261, in struct_to_binary
    packet.append(to_binary(uatype, val))
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 274, in to_binary
    return pack_uatype(vtype, val)
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 192, in pack_uatype
    return variant_to_binary(value)
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 378, in variant_to_binary
    b.append(pack_uatype(var.VariantType, var.Value))
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 188, in pack_uatype
    return extensionobject_to_binary(value)
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 460, in extensionobject_to_binary
    Body = struct_to_binary(obj)
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 261, in struct_to_binary
    packet.append(to_binary(uatype, val))
  File "/home/prathikbhat/Virtual_Environments/data_servers_env/lib/python3.8/site-packages/opcua/ua/ua_binary.py", line 286, in to_binary
    raise UaError("No known way to pack {} of type {} to ua binary".format(val, uatype))
opcua.ua.uaerrors._base.UaError: No known way to pack EUInformation of type EUInformation to ua binary

[prathik-quartic]

@AndreasHeine, I read one of your comments about adding a variable of type EUInformation. I tried it out. I am still getting the same error on the client side as it is not able to interpret AxisInformation datatype.
Could you please take a look at this code and help me out?

[AndreasHeine]

hey,

you need to lookup the classes before using them ^^ the solution is quite simple:

https://reference.opcfoundation.org/v104/Core/DataTypes/AxisInformation/

opcua-asyncio/asyncua/ua/uaprotocol_auto.py

Line 9157 in 51fb682

class AxisInformation:

    units = ua.AxisInformation()
    units.EngineeringUnits = ua.EUInformation()
    units.EURange = ua.Range()
    units.Title = ua.LocalizedText()
    units.AxisScaleType= ua.AxisScaleEnumeration.Linear
    units.AxisSteps = [0.5, 0.75]

[prathik-quartic]

Hey, thank you so much @AndreasHeine . Worked as expected. My bad. Should have gone through the definitions more thoroughly.