How to get list of all published nodes?

[ghost]

Hi, I'm writing Client app and I don't want to hardcode methods to get specific node with ids. I would like to ask server which nodes (variables) are published, I want to get list of each nodes.

How to make it? I was reading example from
https://github.com/FreeOpcUa/python-opcua/blob/master/examples/client-example.py
but I am not sure which methods are necessary. Can you give me tips?

[oroulet]

Every server publishes 1000s of nodes. You do not want to access all of them. The protocol is based on knowing what nodes you want. Ideally using domain specific profiles

[brubbel]

I would just browse the tree upwards starting from the root node.

[zerox1212]

You would need to browse the tree recursively to achieve this.

[ghost]

When I try with:
client.connect()
print ("\nConnected\n")
root = client.get_root_node()
print("%s" %root)
print("Children of root are: %s" %root.get_children())

The answer is:
Node(TwoByteNodeId(i=84))
Children of root are: [Node(TwoByteNodeId(i=87)), Node(TwoByteNodeId(i=85)), Node(TwoByteNodeId(i=86))]

Am I right, that ids of my nodes are: 87,85,86? At least I use:
var = client.get_node(ua.NodeId(85,2))
val = var.get_value()

but there is an error: "The node id refers to a node that does not exist in the server address.."

Could you give me an advise or some example? I read:

https://github.com/FreeOpcUa/python-opcua/blob/master/examples/client-example.py

[brubbel]

root = client.get_root_node()
print("Root node is: {:s} ".format(str(root)))

def browse_recursive(node):
    for childId in node.get_children():
        ch = client.get_node(childId)
        print(ch.get_node_class())
        if ch.get_node_class() == ua.NodeClass.Object:
            browse_recursive(ch)
        elif ch.get_node_class() == ua.NodeClass.Variable:
            try:
                print("{bn} has value {val}".format(
                    bn=ch.get_browse_name(),
                    val=str(ch.get_value()))
                )
            except ua.uaerrors._auto.BadWaitingForInitialData:
                pass

browse_recursive(root)

[ghost]

I still have problems. I receive:

 Root node is Node(TwoByteNodeId(i=84))
 NodeClass.Object
 3
 NodeClass.Object
 3
 NodeClass.Object
 3

I copied your code:

 try:
    root = client.get_root_node()
    print("Root node is {:s} " .format(str(root)))

    def browse_recursive(node):
    for childId in node.get_children():
           ch = client.get_node(childId)
           print(ch.get_node_class())
           if ch.get_node_class == ua.NodeClass.Object:
                   print("1")
                   browse_recursive(ch)
           elif ch.get_node_class() == ua.NodeClass.Variable:
                     print("2")
                     try:
                               print("{bn} has value {val}".format(bn=$
                     except ua.uaerror._auto.BadWaitingForInitialDat$
                               pass
            else:
                      print("3")
    browse_recursive(root)

It looks like NodeClass.Object != ua.NodeClass.Object?
Normally, I use:

    var = client.get_node("ns=2;s=Register1")

to get node and later to get the value. But when I add in the code above:

 for childId in node.get_children():
           ch = client.get_node(childId)
           print(ch.get_node_class())
           print(ch.get_browse_name()) #I added this line

I receive:

 NodeClass.Object
 QualifiedName(0:Views)
 3
 NodeClass.Object
 QualifiedName(0:Objects)
 3
 NodeClass.Object
 QualifiedName(0:Types)
 3

[brubbel]

ch.get_node_class**()** == ua.NodeClass.Object
There is a typo in your code.

[ghost]

Great work, thank you :)

[twodonkeys]

mark

[mukaraT]

@brubbel I tried your code and received the below error. Its because of the variable level/structure I guess. Any idea how to fix it?

(.python_venv) PS C:\Users\Mukara> & d:/Thangz/Projekte/VC/python_venv/.python_venv/Scripts/python.exe d:/Thangz/Projekte/VC/OPC/read_write_OPCUA_thangz.py
Requested session timeout to be 3600000ms, got 30000ms instead
Objects root node is:  i=84
Root node is: i=84
NodeClass.Object
NodeClass.Object
NodeClass.Variable
QualifiedName(0:Auditing) has value True
NodeClass.Method
NodeClass.Variable
QualifiedName(0:NamespaceArray) has value ['http://opcfoundation.org/UA/', 'urn:SIMATIC.S7-1500.OPC-UA.Application:PLC_1', 'http://opcfoundation.org/UA/DI/', 'http://www.siemens.com/simatic-s7-opcua']
NodeClass.Object
NodeClass.Object
NodeClass.Variable
.
.
.
NodeClass.Object
NodeClass.Variable
QualifiedName(3:PT) has value 0
NodeClass.Variable
QualifiedName(3:ET) has value 0
NodeClass.Variable
QualifiedName(3:IN) has value False
NodeClass.Variable
QualifiedName(3:Q) has value False
NodeClass.Object
NodeClass.Variable
QualifiedName(3:4125_6S1) has value ExtensionObject(TypeId:StringNodeId(ns=3;s=TE_"U_StB1"), Encoding:1, 2 bytes)
NodeClass.Variable
QualifiedName(3:4125Man) has value ExtensionObject(TypeId:StringNodeId(ns=3;s=TE_"U_StB1"), Encoding:1, 2 bytes)
NodeClass.Variable
Traceback (most recent call last):
  File "d:\Thangz\Projekte\VC\OPC\read_write_OPCUA_thangz.py", line 58, in <module>
    browse_recursive(root)
  File "d:\Thangz\Projekte\VC\OPC\read_write_OPCUA_thangz.py", line 30, in browse_recursive
    browse_recursive(ch)
  File "d:\Thangz\Projekte\VC\OPC\read_write_OPCUA_thangz.py", line 30, in browse_recursive
    browse_recursive(ch)
  File "d:\Thangz\Projekte\VC\OPC\read_write_OPCUA_thangz.py", line 30, in browse_recursive
    browse_recursive(ch)
  [Previous line repeated 2 more times]
  File "d:\Thangz\Projekte\VC\OPC\read_write_OPCUA_thangz.py", line 35, in browse_recursive
    val=str(ch.get_value()))
  File "D:\Thangz\Projekte\VC\python_venv\.python_venv\lib\site-packages\opcua\common\node.py", line 155, in get_value
    result = self.get_data_value()
  File "D:\Thangz\Projekte\VC\python_venv\.python_venv\lib\site-packages\opcua\common\node.py", line 164, in get_data_value
    return self.get_attribute(ua.AttributeIds.Value)
  File "D:\Thangz\Projekte\VC\python_venv\.python_venv\lib\site-packages\opcua\common\node.py", line 276, in get_attribute
    result[0].StatusCode.check()
  File "D:\Thangz\Projekte\VC\python_venv\.python_venv\lib\site-packages\opcua\ua\uatypes.py", line 218, in check
    raise UaStatusCodeError(self.value)
opcua.ua.uaerrors._auto.BadNotReadable: "The access level does not allow reading or subscribing to the Node."(BadNotReadable)
(.python_venv) PS C:\Users\Mukara> 

Regards,
Mukara

[schroeder-]

You have to check the access level of the node before browsing via:
if ch.get_access_level() & (1<< ua.AccessLevel.CurrentRead.mask):
....
Or just catch the exception and continue

[mukaraT]

I tried with this below function, it is still not able to read the rest of the node ids :(

def browse_recursive(node):
    for childId in node.get_children():
        ch = client.get_node(childId)
        print(ch.get_node_class())
        if ch.get_access_level() & (1<< ua.AccessLevel.CurrentRead.mask):
            if ch.get_node_class() == ua.NodeClass.Object:
                browse_recursive(ch)
            elif ch.get_node_class() == ua.NodeClass.Variable:
                try:
                    print("{bn} has value {val}".format(
                        bn=ch.get_browse_name(),
                        val=str(ch.get_value()))
                    )
                except ua.uaerrors._auto.BadWaitingForInitialData:
                    pass
            

Any Ideas/Suggestions, where I could read all the node IDs or pass the exceptions and read further variables?

Regards,
Mukara

[brubbel]

...
                try:
                    print("{bn} has value {val}".format(
                        bn=ch.get_browse_name(),
                        val=str(ch.get_value()))
                    )
                except ua.uaerrors.UaStatusCodeError as e:
                    print(e)
                    pass
....

[SHAFIT]

I was trying to get the complete list of variables. But it is showing some data which are not really required.
is it possible to browse only the variables which are assinged to a particular "ns". for example "ns=1; "

node = client.get_objects_node()
print("Starting Node: ", node)

def browse_recursive(node):
    for childId in node.get_children():
        ch = client.get_node(childId)
        if ch.get_node_class() == ua.NodeClass.Object:
            browse_recursive(ch)
            #print ("Recusrising ", ch)
        elif ch.get_node_class() == ua.NodeClass.Variable:
            try:
                print ("Node is variable ", ch)
            except ua.uaerrors._auto.BadWaitingForInitialData:
                pass

browse_recursive(node)