Read values from S7-1500 OPC

[bauermarkus]

Hello,

i try to get some values from a Siemens S7-1500 OPC Server

I browse the tag I want to read with the Prosys OPC UA Browser

This is the structure

So tried the following code:

    await client.connect()
    root = client.get_root_node()

    print("Objects node is: %r", root)

    # Node objects have methods to read and write node attributes as well as browse or populate address space
    print(f"Children of root are:")
    for c in await root.get_children():
        print(f'\t{c} {await c.read_display_name()} {await c.read_browse_name()}')

    namespaces = await client.get_namespace_array()
    for ns in namespaces:
        print( f'Index of {ns}: {await client.get_namespace_index(ns)}' )

    # 'ns=3;s="S360 Main Data DB"."Offline Nest"[1]."PDR"."LPC"."Desc"'
    #myvar = await client.nodes.root.get_child('ns=3;s="S360 Main Data DB"."Offline Nest"[1]."PDR"."LPC"."Desc"')
    var = client.get_node("ns=0;i=84")
    value = await var.read_value()
    print(f"Value of MyVariable ({var}): {value}")

My output is:

Objects node is: %r i=84
Children of root are:
        i=85 LocalizedText(Locale=None, Text='Objects') QualifiedName(NamespaceIndex=0, Name='Objects')
        i=86 LocalizedText(Locale=None, Text='Types') QualifiedName(NamespaceIndex=0, Name='Types')
        i=87 LocalizedText(Locale=None, Text='Views') QualifiedName(NamespaceIndex=0, Name='Views')
Index of http://opcfoundation.org/UA/: 0
Index of urn:SIMATIC.S7-1500.OPC-UAServer:PLC: 1
Index of http://opcfoundation.org/UA/DI/: 2
Index of http://www.siemens.com/simatic-s7-opcua: 3

But it does not really matter, I always get a exception:
get_node:

.venv\lib\site-packages\asyncua\ua\uatypes.py", line 372, in check
    raise UaStatusCodeError(self.value)
asyncua.ua.uaerrors._auto.BadAttributeIdInvalid: "The attribute is not supported for the specified Node."(BadAttributeIdInvalid)
Exception ignored in: <function _ProactorBasePipeTransport.__del__ at 0x00000181C1B13040>
Traceback (most recent call last):
  File "C:\Program Files\Python39\lib\asyncio\proactor_events.py", line 116, in __del__
  File "C:\Program Files\Python39\lib\asyncio\proactor_events.py", line 108, in close
  File "C:\Program Files\Python39\lib\asyncio\base_events.py", line 746, in call_soon
  File "C:\Program Files\Python39\lib\asyncio\base_events.py", line 510, in _check_closed
RuntimeError: Event loop is closed

get_child:

.venv\lib\site-packages\asyncua\ua\uatypes.py", line 372, in check
    raise UaStatusCodeError(self.value)
asyncua.ua.uaerrors._auto.BadNoMatch: "The requested operation has no match to return."(BadNoMatch)
Exception ignored in: <function _ProactorBasePipeTransport.__del__ at 0x0000023E1C2F4040>
Traceback (most recent call last):
  File "C:\Program Files\Python39\lib\asyncio\proactor_events.py", line 116, in __del__
  File "C:\Program Files\Python39\lib\asyncio\proactor_events.py", line 108, in close
  File "C:\Program Files\Python39\lib\asyncio\base_events.py", line 746, in call_soon
  File "C:\Program Files\Python39\lib\asyncio\base_events.py", line 510, in _check_closed
RuntimeError: Event loop is closed

Can someone explain me what I am doing wrong?

[bauermarkus]

Ok I need to read the string with the get_node

node = client.get_node('ns=3;s="S360 Main Data DB"."Offline Nest"[1]."PDR"."LPC"."Num"')