set_value to node

[ghost]

as a client i try to set the value of a node on my server like this:

from opcua import Client

url = "opc.tcp://10.0.0.55:4840"
client = Client(url)
client.connect()
Test = client.get_node("n=2;i=5")
Test.set_value(10.0)

On the server "Test" is already set as writeable.

But i always get this error:

Traceback (most recent call last):
  File "/Users/ddd/Documents/workspace/OPCUAclient/client.py", line 25, in <module>
    Test.set_value(10.0)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/opcua/common/node.py", line 214, in set_value
    self.set_attribute(ua.AttributeIds.Value, datavalue)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/opcua/common/node.py", line 259, in set_attribute
    result = self.server.write(params)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/opcua/client/ua_client.py", line 346, in write
    data = self._uasocket.send_request(request)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/opcua/client/ua_client.py", line 78, in send_request
    data = future.result(self.timeout)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/concurrent/futures/_base.py", line 434, in result
    raise TimeoutError()
concurrent.futures._base.TimeoutError

somebody may know whats happening here?

thx cheers

[zerox1212]

What server are you using?

[ghost]

i wrote a server using opcua like this:

from opcua import Server

server = Server()

url = "opc.tcp://10.0.0.55:4840"
server.set_endpoint(url)

name = "OPCUA_SERVER"
addspace = server.register_namespace(name)

node = server.get_objects_node()

Param = node.add_object(addspace, "Parameters")

Test = Param.add_variable(addspace, "Test", 0)

Test.set_writable()

server.start()

thanks!

[Muzhai]

I encountered the same problem. Have you found the cause of the problem?

[AndreasHeine]

reading and writing nodes works! so please provide more details code snippets and what server type!? variable type please make sure if you create variables to provide a propper variant format otherwise it can make problems because python is dynamicly typed and opcua is strict typed! lg

[Muzhai]

I used the “python-opcua/examples/server-minimal.py” as a test Server. This is working gut and the function set_value is no problem too. But when i try to write certain values through "client-minimal.py" occurred the Error "concurrent.futures._base.TimeoutError".

The Client lick this import sys sys.path.insert(0, "..")

import time from opcua import ua, Client

if name == "main":

client = Client("opc.tcp://localhost:4845/freeopcua/server/")
# client = Client("opc.tcp://admin@localhost:4840/freeopcua/server/") #connect using a user
try:
    client.connect()

    # Client has a few methods to get proxy to UA nodes that should always be in address space such as Root or Objects
    root = client.get_root_node()
    print("Root node is: ", root)

    # Node objects have methods to read and write node attributes as well as browse or populate address space
    print("Children of root are: ", root.get_children())

    # get a specific node knowing its node id
    var = client.get_node(ua.NodeId(1, 2))
    print(var)
    # var = client.get_node("ns=2;i=1")
    #print('value', var.get_data_value())# get value of node as a DataValue object
    #var.get_value() # get value of node as a python builtin
    #var.set_value(ua.Variant([50], ua.VariantType.Double)) #set node value using explicit data type
    var.set_value(11) # set node value using implicit data type

    # Now getting a variable node using its browse path
    myvar = root.get_child(["0:Objects", "2:MyObject", "2:MyVariable"])
    obj = root.get_child(["0:Objects", "2:MyObject"])
    print("myvar is: ", myvar)
    print("myobj is: ", obj)

    # Stacked myvar access
    print("myvar is: ", root.get_children()[0].get_children()[1].get_variables()[0].get_value())

finally:
    client.disconnect()

[AndreasHeine]

could you tell me which one causes that? so i can try to reproduce?

[Muzhai]

This is the Server

import sys sys.path.insert(0, "..") import time

from opcua import ua, Server server = Server() server.set_endpoint("opc.tcp://0.0.0.0:4845/freeopcua/server/") objects = server.get_objects_node() uri = "http://examples.freeopcua.github.io" idx = server.register_namespace(uri)

populating our address space

myobj = objects.add_object(idx, "MyObject") myvar = myobj.add_variable(idx, "MyVariable", 6.7) myvar.set_writable() # Set MyVariable to be writable by clients print(myvar)

starting!

server.start() try: count = 0 while True: time.sleep(1) count += 0.1 myvar.set_value(count) finally:

close connection, remove subcsriptions, etc

server.stop()

[Muzhai]

This is the Error: Traceback (most recent call last): File "D:/Masterarbeit/program/MA_OPC_UA/OPC_UA_Client.py", line 31, in var.set_value(11) # set node value using implicit data type File "D:\Programm\Python\lib\site-packages\opcua\common\node.py", line 217, in set_value self.set_attribute(ua.AttributeIds.Value, datavalue) File "D:\Programm\Python\lib\site-packages\opcua\common\node.py", line 262, in set_attribute result = self.server.write(params) File "D:\Programm\Python\lib\site-packages\opcua\client\ua_client.py", line 367, in write data = self._uasocket.send_request(request) File "D:\Programm\Python\lib\site-packages\opcua\client\ua_client.py", line 83, in send_request data = future.result(self.timeout) File "D:\Programm\Python\lib\concurrent\futures_base.py", line 434, in result raise TimeoutError() concurrent.futures._base.TimeoutError

[Muzhai]

Fist of all thank you for your help , I am a newbie, recently I am work with OPCUA and that makes me excited and depressed:)

[AndreasHeine]

var = client.get_node(ua.NodeId(1, 2)) <--- is type object and not variable you can only write variables!

you should use uaexpert to check the ids befor try to write them var = client.get_node(ua.NodeId(2, 2))

to simplify you can client.get_node("ns=2;i=2")

[Muzhai]

Thank you very much, the problem has been resolved. :)))